Angular 8

Angular 8 is the latest version of Angular, this course starts from scratch, from setup to deployment. This course will help you to learn all about components, directives, services, forms, HTTP access, authentication, optimizing an Angular app with modules and offline compilation, and much more.

Q.1 How can you create a pure pipe in Angular 8?
In Angular 8, a pure pipe is a pipe that is stateless and doesn't change its output based on mutable data. To create a pure pipe, you set the pure property of the @Pipe decorator to true. Pure pipes are optimized for performance as they are only executed when the input data changes.
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Q.2 What is the difference between pure and impure pipes in Angular 8?
The main difference between pure and impure pipes in Angular 8 is how they handle changes. Pure pipes are only executed when the input data changes, while impure pipes are executed on every change detection cycle, even if the input data remains the same. Impure pipes can cause performance issues and should be used with caution.
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Q.3 How can you handle data transformation that requires complex logic in Angular 8 pipes?
If you have a data transformation that requires complex logic, it is recommended to handle it in a component or service instead of a pipe. Pipes are meant for simple data transformations and should not contain complex business logic. You can create a custom method in a component or service and call that method in the template.
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Q.4 How can you localize or translate text using pipes in Angular 8?
To localize or translate text using pipes in Angular 8, you can use the i18n pipe along with the Angular Internationalization (i18n) feature. The i18n pipe allows you to display translated text based on the user's locale.
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Q.5 What are dynamic components in Angular 8?
Dynamic components in Angular 8 refer to the ability to create and render components dynamically at runtime. Unlike statically defined components, dynamic components allow for dynamic composition and rendering of components based on certain conditions or user interactions.
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Q.6 How can you create a dynamic component in Angular 8?
To create a dynamic component in Angular 8, you need to define the component class, template, and metadata just like any other component. Then, you can use the ComponentFactoryResolver to create an instance of the component dynamically. Finally, you can use the ViewContainerRef to insert the component into the desired location in the DOM.
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Q.7 How can you pass data to a dynamic component in Angular 8?
You can pass data to a dynamic component by using the componentRef.instance property. After creating an instance of the dynamic component, you can set its properties or call methods by accessing the instance property and passing the required data.
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Q.8 How can you destroy a dynamic component in Angular 8?
To destroy a dynamic component in Angular 8, you can use the ComponentRef obtained during the component creation process. You can call the destroy() method on the ComponentRef to remove the component from the DOM and clean up any associated resources.
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Q.9 What is the difference between static and dynamic components in Angular 8?
Static components are defined in the template of a parent component and are known at compile-time. They are part of the component's view and are always present. On the other hand, dynamic components are created and rendered programmatically at runtime. They provide flexibility in terms of composition and rendering based on dynamic conditions.
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Q.10 How can you dynamically load a component template in Angular 8?
In Angular 8, you can dynamically load a component template by using the TemplateRef and ViewContainerRef classes. The TemplateRef represents the template to be loaded, and the ViewContainerRef represents the location in the DOM where the template should be inserted. You can use methods like createEmbeddedView or createComponent to load the template dynamically.
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Q.11 How can you dynamically add or remove dynamic components in Angular 8?
To dynamically add or remove dynamic components in Angular 8, you can use the ViewContainerRef and the methods it provides. The createComponent method allows you to add a dynamic component, while the remove method allows you to remove a dynamic component from the DOM.
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Q.12 Can you provide dependencies to dynamic components in Angular 8?
Yes, you can provide dependencies to dynamic components in Angular 8. You can use the Injector to provide dependencies when creating an instance of the dynamic component. By configuring the providers array, you can supply the required dependencies to the component.
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Q.13 How can you handle events from dynamic components in Angular 8?
To handle events from dynamic components in Angular 8, you can use event binding and event emitters. You can define custom events in the dynamic component and emit events using EventEmitter. In the parent component, you can use event binding to listen to these events and perform the desired actions.
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Q.14 How can you dynamically load different components based on a condition in Angular 8?
To dynamically load different components based on a condition in Angular 8, you can use structural directives like ngIf or ngSwitch along with dynamic component creation. By evaluating the condition and using the appropriate template or component dynamically, you can render different components based on runtime conditions.
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Q.15 What are Angular modules in Angular 8?
Angular modules in Angular 8 are a way to organize and package related components, directives, pipes, and services into cohesive units. They provide a mechanism for code modularization, reusability, and separation of concerns within an Angular application.
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Q.16 How can you create a module in Angular 8?
To create a module in Angular 8, you can use the ng generate module command or manually create a new TypeScript file with the .module.ts extension. In the module file, you define the module class using the @NgModule decorator and configure its imports, declarations, providers, and exports.
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Q.17 What is the purpose of the imports array in an Angular module?
The imports array in an Angular module is used to specify other modules that the current module depends on. By importing other modules, you can make their components, directives, and services available for use within the current module.
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Q.18 What is the purpose of the declarations array in an Angular module?
The declarations array in an Angular module is used to specify the components, directives, and pipes that belong to the current module. By declaring these entities, you make them available for use within the module and its components.
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Q.19 What is the purpose of the providers array in an Angular module?
The providers array in an Angular module is used to configure the dependency injection system and specify the services that are provided by the module. By adding providers to this array, you make the services available for injection throughout the module and its components.
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Q.20 What is the purpose of the exports array in an Angular module?
The exports array in an Angular module is used to specify the components, directives, and pipes that should be available for use in other modules. By exporting these entities, you make them accessible to other modules that import the current module.
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Q.21 What is the difference between a shared module and a feature module in Angular 8?
A shared module in Angular 8 is a module that contains common components, directives, and pipes that are used across multiple feature modules. It helps avoid code duplication and promotes reusability. On the other hand, a feature module is a module that represents a specific feature or functionality of an application. It encapsulates components, directives, and services related to that feature.
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Q.22 How can you lazy load a module in Angular 8?
To lazy load a module in Angular 8, you can use the loadChildren property in the route configuration. By specifying the path to the module file using the loadChildren property, the module and its associated components will be loaded on-demand when the corresponding route is accessed.
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Q.23 Can you have multiple modules in an Angular application?
Yes, an Angular application can have multiple modules. In fact, modularization is a recommended approach in Angular to keep the codebase organized, maintainable, and scalable. Each module can represent a specific area or feature of the application.
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Q.24 How can you share data between modules in Angular 8?
To share data between modules in Angular 8, you can use services. Services act as a centralized data store and can be injected into multiple modules. By storing the shared data in a service, you can access and update it from different modules, allowing for efficient data sharing and communication.
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Q.25 What is NgRx?
NgRx is a state management library for Angular applications inspired by Redux. It provides a predictable state container, actions, reducers, and selectors to manage application state in a centralized manner.
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Q.26 Why would you use NgRx in an Angular application?
NgRx helps in managing complex application state and enables a unidirectional data flow. It promotes a scalable and maintainable architecture by separating concerns and providing a clear separation between state and UI.
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Q.27 What are the core building blocks of NgRx?
The core building blocks of NgRx are actions, reducers, selectors, and effects. Actions are plain objects that represent an event or command, reducers handle state changes based on actions, selectors provide a way to retrieve specific parts of the state, and effects handle side effects such as API calls.
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Q.28 What is an action in NgRx?
Actions are simple objects that describe an event or command that triggers state changes in NgRx. They typically have a type property that describes the action's purpose and may contain additional payload data.
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Q.29 What is a reducer in NgRx?
Reducers are pure functions that take the current state and an action as input and produce a new state as output. They define how the state should change in response to different actions.
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Q.30 What are selectors in NgRx?
Selectors are functions that extract specific data from the state. They provide a way to access specific parts of the state tree without directly accessing the state itself, enabling better decoupling between components and the state.
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Q.31 What is an effect in NgRx?
Effects handle side effects, such as asynchronous operations, in NgRx. They listen for specific actions and can perform tasks like making HTTP requests, interacting with external APIs, or dispatching additional actions.
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Q.32 How do you dispatch an action in NgRx?
To dispatch an action in NgRx, you can use the store's dispatch method, passing in the action object. For example, this.store.dispatch({ type: 'INCREMENT' }) dispatches an action with type 'INCREMENT'.
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Q.33 What is the purpose of @ngrx/store-devtools in NgRx?
The @ngrx/store-devtools is a browser extension that provides a user interface to monitor and debug the application's state changes. It allows developers to inspect the dispatched actions, track state history, and replay actions for debugging purposes.
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Q.34 How can you handle asynchronous operations in NgRx?
You can handle asynchronous operations in NgRx by using effects. Effects provide a way to listen for specific actions and perform side effects such as making API calls. Within effects, you can dispatch new actions based on the result of the asynchronous operation.
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Q.35 What are Angular Animations?
Angular Animations is a module provided by Angular that allows you to create rich and interactive animations within your Angular applications. It provides a way to define animations for various states and transitions of DOM elements.
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Q.36 How do you define an animation in Angular?
To define an animation in Angular, you can use the trigger() function from the @angular/animations package. It takes a unique name for the animation and an array of animation steps or styles to define the animation's behavior.
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Q.37 What are the different types of animation states in Angular?
There are four types of animation states in Angular: void, initial, and any custom states you define. The void state represents the element before it enters the DOM, the initial state represents the element's state when it first enters the DOM, and custom states represent specific states you define in your animation.
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Q.38 How can you apply animations to an element in Angular?
You can apply animations to an element in Angular by using the [@triggerName] syntax in the template. For example,
Content
applies the animation with the trigger name "fadeInOut" to the
element.
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Q.39 What are animation keyframes?
Animation keyframes define the intermediate steps or styles between the start and end points of an animation. They allow you to create more complex animations with multiple states and transitions.
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Q.40 How can you create a transition between two states in Angular?
To create a transition between two states in Angular, you can use the transition() function within a trigger() block. It takes the states to transition from and to, along with the animation steps or styles for the transition.
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Q.41 What is the difference between the state() and style() functions in Angular animations?
The state() function is used to define a specific state of an element, while the style() function is used to define the CSS styles for an element. The state() function is typically used within transition() to specify the states being transitioned.
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Q.42 How can you animate the entry and exit of an element in Angular?
You can animate the entry and exit of an element in Angular using the void state. By defining animations for the void => * transition, you can control how an element enters the DOM, and by defining animations for the * => void transition, you can control how an element exits the DOM.
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Q.43 What are animation groups in Angular?
Animation groups allow you to run multiple animations simultaneously. By wrapping animations within a group() function, you can synchronize the execution of multiple animations.
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Q.44 How can you control the timing and easing of an animation in Angular?
You can control the timing and easing of an animation in Angular by using the duration(), delay(), and easing() functions within animation steps. These functions allow you to specify the duration, delay, and easing function for the animation.
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Q.45 What is a Service Worker?
A Service Worker is a JavaScript file that runs in the background of a web browser and acts as a programmable proxy between the web application and the network. It allows developers to implement features such as offline support, push notifications, and background synchronization.
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Q.46 How do you register a Service Worker in Angular?
To register a Service Worker in Angular, you can use the serviceWorker.register() method provided by the @angular/service-worker package. It is typically done in the main.ts file of the Angular application.
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Q.47 What is the purpose of a ngsw-config.json file?
The ngsw-config.json file is used to configure the behavior of the Angular Service Worker. It defines various settings such as the cache strategies, routes to be cached, and assets to be preloaded.
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Q.48 What is the difference between an App Shell and a Service Worker in Angular?
An App Shell is a design pattern that allows you to render a minimal HTML and CSS structure of your application while the remaining content is loaded asynchronously. A Service Worker, on the other hand, is a background script that runs independently and handles tasks like caching and offline support.
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Q.49 How does a Service Worker enable offline support in an Angular application?
A Service Worker can cache the necessary resources of an Angular application when it is first loaded. When the user goes offline, the Service Worker can intercept network requests and serve the cached resources, allowing the application to continue functioning even without an internet connection.
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Q.50 What is the update process for a Service Worker in Angular?
When an Angular application with a Service Worker is updated, the browser checks for updates to the Service Worker script. If a new version is found, it is downloaded and installed in the background. The new Service Worker becomes active when all tabs using the old Service Worker are closed.
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Q.51 How can you communicate between an Angular application and a Service Worker?
You can use the postMessage() API to send messages between an Angular application and a Service Worker. The Angular application can send messages to the Service Worker to trigger specific actions or receive information from the Service Worker.
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Q.52 What are the different caching strategies supported by the Angular Service Worker?
The Angular Service Worker supports various caching strategies, including the Network First, Cache First, Cache Only, and Network Only strategies. These strategies determine how requests are handled and whether the Service Worker should use cached responses or fetch new ones.
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Q.53 How can you handle push notifications with a Service Worker in Angular?
To handle push notifications with a Service Worker in Angular, you need to subscribe to push notifications and handle the incoming push events. The Service Worker can show notifications to the user and perform actions based on the received push data.
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Q.54 How can you test Service Workers in Angular applications?
You can test Service Workers in Angular applications by using tools like Chrome DevTools and Lighthouse. These tools allow you to simulate offline scenarios, inspect Service Worker registrations, and debug Service Worker-related issues.
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Q.55 What is unit testing?
Unit testing is a software testing technique where individual components or units of code are tested in isolation to ensure their functionality is working as expected. It focuses on testing the smallest units of code, such as functions or methods, in order to identify any bugs or issues early in the development process.
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Q.56 What is the purpose of unit testing in Angular?
Unit testing in Angular helps ensure the correctness and reliability of individual components, services, and classes. It allows developers to verify that each unit of code performs its intended functionality and catches bugs before they propagate to other parts of the application.
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Q.57 What is the testing framework used in Angular?
Angular uses the Jasmine testing framework as its default choice for unit testing. Jasmine provides a rich set of functions and utilities to write and execute tests in an Angular application.
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Q.58 How do you create a unit test in Angular?
To create a unit test in Angular, you typically create a separate .spec.ts file for each component or service you want to test. Within the test file, you write test cases using Jasmine's testing syntax, such as describe, it, and expect.
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Q.59 What is TestBed in Angular unit testing?
TestBed is an Angular testing utility that provides a testing environment for creating and configuring Angular components. It allows you to compile and instantiate components, provide dependencies, and interact with the component's DOM.
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Q.60 How can you test an Angular component's template?
You can test an Angular component's template by using the ComponentFixture and TestBed utilities. The ComponentFixture provides access to the component instance and its associated DOM, allowing you to interact with the template and verify its behavior.
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Q.61 What is a mock in unit testing?
A mock is a simulated object or behavior that is used to replace dependencies or external components during unit testing. Mocks allow you to isolate the unit under test and control its environment, ensuring consistent and predictable test results.
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Q.62 How can you test asynchronous code in Angular?
Angular provides the async and fakeAsync utilities to test asynchronous code. The async utility is used with the await keyword to handle Promises, while the fakeAsync utility allows you to simulate the passage of time using the tick function.
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Q.63 What is code coverage in unit testing?
Code coverage is a measure of the percentage of code that is executed during the execution of tests. It helps identify areas of code that are not adequately covered by tests. Tools like Istanbul or the built-in Angular CLI can generate code coverage reports for Angular applications.
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Q.64 How can you run unit tests in Angular?
You can run unit tests in Angular by using the Angular CLI command ng test. This command launches the Karma test runner, which executes the tests defined in the .spec.ts files and provides feedback on the test results.
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Q.65 What is angular 8 used for?
Angular 8 is the most recent version, which was released by the Angular community on May 28, 2019. It is the most well-known client-side TypeScript-based framework for developing dynamic web apps. Angular 8 is quite similar to the previous version of Angular, however it has a few new capabilities. You can also easily upgrade your Angular CLI to Angular version 8.
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Q.66 What are the most important features of Angular 8?
The following are the important features of Angular 8: To create two separate production bundles for your app, use Differential Loading. Imports now have new Dynamic Lazy Loading modules. Web Workers are supported. Version 3.4 of TypeScript is supported. New Workspace APIs and Builder are now available. Support for Bazel. Usage sharing with permission. The Ivy Rendering Engine is Angular 8's new compiler.
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Q.67 Is TypeScript 3.4 supported by Angular 8?
Since TypeScript 3.4 is mostly used to run Angular 8 projects, Angular version 8 supports it. In Angular 8, everything is written in TypeScript. As a result, you'll need to upgrade to TypeScript 3.4.
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Q.68 In Angular 8, what is Ivy?
The Rendering Engine in Angular version 8 is Ivy. Opt-in was introduced in Angular 8. It has been chosen as the code name for Angular's next-generation rendering and compilation pipeline. In Angular 9, Ivy is supposed to be the rendering engine by default.
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Q.69 In Angular 8, what is the main use of a Bazel?
Bazel is one of the most important features of Angular 8. It always enables you to swiftly create CLI applications. Bazel is a building tool that was created and is primarily utilised by Google since it can create applications in any language. Bazel is used to create the whole Angular framework. Furthermore, Bazel allows you to divide an application into many build units that are defined at the NgModule level.
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Q.70 In Angular 8, what is the purpose of Codelyzer?
Codelyzer is an open-source tool that sits on top of TSLint in Angular version 8. The primary goal of Codelyzer is to determine whether or whether Angular TypeScript 3.4 projects adhere to a set of linting standards. It mostly focuses on Angular TypeScript's static code. In basic terms, the main objective of the Codelyzer in Angular version 8 is to examine the program's quality and validity.
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Q.71 In Angular 8, what is the purpose of the Wildcard Route?
The Wildcard Router in Angular 8's main function is to match every URL as an instruction in order to achieve a clear client-generated display. This Wildcard route is always last because it has to complete its mission at the very end. In Angular 8, it's mostly used to define the page's route.
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Q.72 Which command is used to find out what version of Angular CLI is currently installed?
To check the current version of Angular CLI, use the ng -version command.
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Q.73 What are the benefits of using Bazel?
The following are some of Bazel's primary advantages: It gives you the option of creating both frontends and backends with the same tool. The capacity to develop and test incrementally. On the build farm in Bazel, you have the option of using cache and remote builds.
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Q.74 What are the limitations of Angular 8's web workers?
In Angular version 8, web workers are mostly utilised to speed up the work of items in your application while the CPU is busy. These web workers are mostly used to conduct CPU tasks in the background. This frees up the main thread, allowing it to refresh the user interface.
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Q.75 To execute and load the Angular App, what command is used?
To execute and load the Angular App, use the command ng serve.
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Q.76 What are the most important components of the Angular 8 Architecture?

The following are the main components of the Angular 8 Architecture:

  • Modules Components
  • Templates
  • MetaData
  • Data-Binding
  • Directives Services
  • Dependency Injection
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Q.77 What are the benefits of using Angular 8 components?
In Angular 8, components are a collection of classes with decorators that primarily mark their own types and offer metadata to help Angular do its job. In Angular, every application has at least one component known as a root component. This root component is mostly used to link the page hierarchy to the DOM of the page.
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Q.78 In Angular 8, what are NgModules?
NgModules differ from ordinary JavaScript modules in Angular version 8. AppModule is a module that is present in every Angular app. The NgModule has a bootstrap mechanism that may be used to run various apps. Every Angular App, on the whole, has a lot of functional modules. The following are the primary characteristics of Angular 8 modules: The NgModule's own functionality can be exported and reused by other NgModules. Functionalities from other NgModules can be imported into the Angular 8 NgModule.
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Q.79 In Angular 8, what is the purpose of the nglf directive?
In Angular Version 8, the nglf directive is a structural directive. The expression statement is mostly used to add or remove HTML components with this directive. When the expression is true, the element is added, and when the expression is false, the element is deleted using the nglf directive.
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Q.80 In Angular 8, what is typeofchecks?
In Angular 8, the typeofchecks function is quite important. It is mostly used to ensure that the type of value supplied to the variable is the same as that of JavaScript. In version 8, you can also use typeofchecks to test the value assigned to the object.
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Q.81 In Angular 8, what is the purpose of the ngSwitch directive?
In Angular Version 8, it's also a Structural directive. ngSwitch is mostly used to add and delete HTML DOM elements. It's very similar to Cswitch #'s statement. A switch expression is used to apply this directive to a container element.
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Q.82 In Angular 8, what is Data Binding?
In Angular 8, data binding is an important concept that is mostly utilised to construct communication between the DOM and the TypeScript code of your component. It's the most common method for connecting your data to the view layer. Data binding can also be used to quickly and easily create interactive applications. One-way binding or two-way binding can be used to accomplish this.
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Q.83 What is the purpose of the ngSwitch directive?
It's also a Structural directive. ngSwitch is mostly used to add and delete HTML DOM elements. It's very similar to Cswitch #'s statement. A switch expression is used to apply this directive to a container element.
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Q.84 What is the purpose of Event Binding?
The Event Binding approach is primarily used to handle DOM events like as mouse movement, button click, and many more. When a DOM event happens, only the defined method in the component is called at that time.
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Q.85 What are the primary goals of Angular 8 forms?
Angular 8 forms are mostly used to process user input. These forms can also be used in your applications to allow users to login, submit personal information, update profiles, and complete other data entry jobs, among other things. In general, there are two techniques of using forms to handle user input. The two ways are used to collect user input from the display layer and give a way to track various changes.
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Q.86 Why are reactive forms used?
Since the following functionalities, reactive forms are used in Angular 8. They are as follows: Testable, scalable, and reusable, reactive forms are a great way to go. They're more durable. When the forms are the most important aspect of your application, they are usually favoured.
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Q.87 In Angular 8, why do we need Template-driven forms?
In Angular 8, template-driven forms are required in the following scenarios. Template-driven forms are required if you only wish to add a simple form to your application. Although they are simple to employ in applications, they are not scalable. Template-driven forms should be used if any of your apps require very basic logic and form.
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Q.88 What is an Angular Universal, and how does it work?
The Angular Universal is the process of converting your application's SSR (server-side rendering) to HTML on the server. Because all Angular applications are single-page applications, rendering takes place entirely in the browser. The client-side rendering process encompasses the complete process of rendering single-page apps (CSR).
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Q.89 What are the benefits of using Angular 8?
The following are some of the advantages of Angular 8: Improved performance Debugging templates for clean code development Multiple apps in a single domain are supported by Angular 8. easy to put into practise
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Q.90 What is Bazel's purpose in Angular 8?
Bazel is an Angular 8 build mechanism that is only accessible for a limited time. It offers a platform for creating both back-end and front-end services using the same tool. It enables us to rapidly and simply create CLI (Command Line Interface) apps. The Bazel architecture underpins the whole Angular 8 framework, allowing us to partition an application into distinct build units defined at the NgModule level. It allows for customization as well as the creation of graphs. We may utilise these graphs to quickly discover the most important data.
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Q.91 What are your thoughts on Ivy in Angular 8?
Ivy is Angular 8's rendering engine. Ivy was introduced as an opt-in feature in Angular 8 and was also chosen as the code name for Angular's next-generation rendering pipeline and compilation.
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Q.92 In Angular 8, what is CodeLyzer?
Codelyzer is an open-source tool that is built on the TSLint base. It checks if the Angular TypeScript 3.4 projects adhere to a set of linting criteria, ensuring that the programmes' quality and correctness are not jeopardised.
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Q.93 Explain why the WildCard Route is important in Angular 8.
Angular 8 WildCard Route is responsible for matching URLs as instructions in order to build a client-generated display. When the requested URL does not match any of the router pathways, it creates a route. In a nutshell, the WildCard Router in Angular 8 defines or sets the routes of the pages.
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Q.94 Why are template-driven forms used?
Template-driven forms in Angular 8 are used to add simple forms to applications when scalability is not a concern. They're quite simple to use, however they're not as scalable as Reactive forms.
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Q.95 What is string interpolation in Angular 8?
String interpolation in Angular 8 is a convenient way to embed expressions within template literals or double curly braces ({{}}). It allows you to dynamically bind values from component properties to the template, making it easier to display and manipulate data.
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Q.96 How do you perform string interpolation in Angular 8?
To perform string interpolation in Angular 8, you can use the double curly braces ({{}}) syntax. Inside the braces, you can include an expression that will be evaluated and the result will be inserted into the template.
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Q.97 How can you perform property binding using string interpolation in Angular 8?
String interpolation can also be used for property binding in Angular 8. You can bind a property of an HTML element to an expression by using the double curly braces syntax.
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Q.98 Is it possible to use string interpolation in attribute values in Angular 8?
Yes, string interpolation can be used in attribute values as well. You can include expressions within attribute values by using the double curly braces syntax.
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Q.99 Can you use ternary operators within string interpolation expressions in Angular 8?
Yes, you can use ternary operators within string interpolation expressions in Angular 8. This allows you to conditionally display different values based on the evaluation of an expression.
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Q.100 How can you concatenate strings within string interpolation in Angular 8?
To concatenate strings within string interpolation in Angular 8, you can use the concatenation operator (+).
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Q.101 Can you perform method calls within string interpolation expressions in Angular 8?
No, you cannot directly call methods within string interpolation expressions in Angular 8. String interpolation is meant for simple expressions and property access. If you need to perform more complex logic or method calls, it is recommended to do so in the component's code and bind the result to a property that can be used in string interpolation.
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Q.102 What is the difference between string interpolation and property binding in Angular 8?
String interpolation and property binding are similar in that they both allow you to dynamically bind values to the template. The main difference is in the syntax used. String interpolation uses double curly braces ({{}}) and is typically used for displaying values in the template, while property binding uses square brackets ([]) and is used for binding properties of HTML elements to component properties.
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Q.103 Can you use Angular expressions within string interpolation in Angular 8?
No, Angular expressions (such as ngIf or ngFor) cannot be used directly within string.
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Q.104 What is property binding in Angular 8?
Property binding in Angular 8 is a mechanism that allows you to bind a property of an HTML element to a value or expression in the component. It enables you to dynamically update the property based on changes in the component, providing a way to interact between the component and the template.
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Q.105 How do you perform property binding in Angular 8?
To perform property binding in Angular 8, you use square brackets ([]) around the property name within the HTML element. The value or expression to be bound is then assigned to the property inside the square brackets.
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Q.106 Can you bind a component property to an attribute in Angular 8?
Yes, you can bind a component property to an attribute in Angular 8 using property binding. By using the square brackets syntax, you can bind a property to an attribute value.
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Q.107 Can you bind to a class or style property using property binding in Angular 8?
Yes, you can bind to class or style properties using property binding in Angular 8. To bind to a class, you can use the class attribute and bind it to a property that returns a string of CSS classes. To bind to a style, you can use the style attribute and bind it to a property that returns an object with CSS styles.
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Q.108 How can you bind to event properties using property binding in Angular 8?
You can bind to event properties using property binding in Angular 8. By using the square brackets syntax, you can bind an event property to a method in the component.
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Q.109 Can you perform two-way binding using property binding in Angular 8?
Yes, you can perform two-way binding using property binding in Angular 8 by using the [(ngModel)] syntax. Two-way binding allows you to bind both the property and the event of an element.
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Q.110 Is it possible to bind to a component's input property using property binding?
Yes, you can bind to a component's input property using property binding. By using the square brackets syntax, you can bind the input property of a component to a value or expression in the parent component's template.
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Q.111 What is event binding in Angular 8?
Event binding in Angular 8 is a mechanism that allows you to respond to user interactions or events, such as button clicks, mouse movements, or keyboard inputs. It enables you to bind a method in the component to an event in the template, allowing you to handle and react to user actions.
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Q.112 How do you perform event binding in Angular 8?
To perform event binding in Angular 8, you use parentheses (()) around the event name within the HTML element. Inside the parentheses, you specify the method to be executed when the event occurs.
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Q.113 Can you pass event data to the event handler using event binding in Angular 8?
Yes, you can pass event data to the event handler using event binding in Angular 8. By including the $event object as an argument in the method call, you can access the event data within the component.
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Q.114 How can you prevent the default behavior of an event using event binding in Angular 8?
To prevent the default behavior of an event using event binding in Angular 8, you can call the preventDefault() method on the event object within the event handler method.
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Q.115 Can you bind to custom events using event binding in Angular 8?
Yes, you can bind to custom events using event binding in Angular 8. Custom events are events that are emitted by a component and can be subscribed to by parent components. By using the parentheses syntax, you can bind to custom events and specify the method to handle the event.
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Q.116 How can you bind to key events using event binding in Angular 8?
You can bind to key events using event binding in Angular 8. Key events include events such as keyup, keydown, and keypress. By using the parentheses syntax, you can bind the desired key event to a method in the component.
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Q.117 Is it possible to bind to multiple events using event binding in Angular 8?
Yes, it is possible to bind to multiple events using event binding in Angular 8. You can separate multiple events with a comma (,) within the parentheses and specify the corresponding methods to handle each event.
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Q.118 How can you pass data from a template to an event handler method using event binding in Angular 8?
To pass data from a template to an event handler method using event binding in Angular 8, you can use template reference variables or pass data as an argument. Template reference variables allow you to reference an element or component in the template and access its properties or methods. You can also pass data directly as an argument in the method call.
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Q.119 How can you pass data from a component to an event handler method using event binding in Angular 8?
To pass data from a component to an event handler method using event binding in Angular 8, you can use the component's properties. Bind the property to a value or expression, and the event handler method can access and utilize that data.
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Q.120 How can you use the passed data in the event handler method in Angular 8?
In the event handler method in Angular 8, you can access and use the passed data by specifying it as an argument in the method signature. Within the method, you can perform any necessary logic or operations using the passed data.
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Q.121 Can you pass multiple data values to an event handler method using event binding in Angular 8?
Yes, you can pass multiple data values to an event handler method using event binding in Angular 8. You can pass multiple values by including them as separate arguments within the parentheses of the event binding.
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Q.122 How can you pass data to a custom event handler method using event binding in Angular 8?
To pass data to a custom event handler method using event binding in Angular 8, you can include the data as an argument within the parentheses when emitting the custom event. In the parent component's template, you can then bind the custom event to the custom event handler method and access the passed data within that method.
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Q.123 Can you use template expression syntax to manipulate or preprocess the data before passing it to an event handler method?
Yes, you can use template expression syntax to manipulate or preprocess the data before passing it to an event handler method. Within the parentheses of the event binding, you can include template expressions that modify or process the data before it is passed to the method.
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Q.124 How do you make HTTP requests in Angular 8?
In Angular 8, you can make HTTP requests using the HttpClient module. First, you need to import the HttpClient module from @angular/common/http. Then, you can inject the HttpClient service into your component or service and use its methods, such as get(), post(), put(), and delete(), to make HTTP requests to a server.
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Q.125 What is the role of the HttpClientModule in Angular 8?
The HttpClientModule in Angular 8 is a built-in module that provides the necessary services and features for making HTTP requests. It encapsulates the HttpClient service, which is used to send HTTP requests and handle responses.
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Q.126 How can you send a GET request using HttpClient in Angular 8?
To send a GET request using HttpClient in Angular 8, you can use the get() method of the HttpClient service. The get() method takes a URL as a parameter and returns an Observable that represents the response from the server. You can subscribe to this Observable to retrieve the data.
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Q.127 How can you send a POST request using HttpClient in Angular 8?
To send a POST request using HttpClient in Angular 8, you can use the post() method of the HttpClient service. The post() method takes a URL and the data to be sent as the request body. It also returns an Observable representing the response.
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Q.128 How can you handle errors in HTTP requests using HttpClient in Angular 8?
To handle errors in HTTP requests using HttpClient in Angular 8, you can use the subscribe() method of the Observable returned by the HTTP request. The subscribe() method takes multiple callbacks, including an error callback where you can handle any errors that occur during the request.
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Q.129 How can you include headers in HTTP requests using HttpClient in Angular 8?
To include headers in HTTP requests using HttpClient in Angular 8, you can pass an options object as the last parameter of the HTTP request methods. The options object can include a headers property where you can define the headers to be sent with the request.
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Q.130 How can you handle query parameters in HTTP requests using HttpClient in Angular 8?
To handle query parameters in HTTP requests using HttpClient in Angular 8, you can append them to the URL string when making the request. Angular's HttpClient will automatically encode the parameters for you.
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Q.131 How does Angular handle error messages?
In Angular, error messages can be handled in various ways. Angular provides mechanisms to catch and handle errors at different levels, such as global error handling, error handling in components, and error handling in services. By utilizing error handling techniques, you can provide meaningful error messages to users and log errors for debugging and troubleshooting.
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Q.132 What is global error handling in Angular 8?
Global error handling in Angular 8 involves intercepting and handling errors that occur throughout the application. By creating a global error handler service and implementing the ErrorHandler interface, you can override the default error handling behavior and provide your own logic to handle errors. This allows you to centralize error handling and customize error messages for the entire application.
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Q.133 How can you display error messages in Angular 8 components?
In Angular 8 components, you can display error messages by using conditional rendering and template bindings. By storing error messages in component properties or retrieving them from services, you can dynamically display error messages in the template based on certain conditions, such as validation errors or API response errors. This approach allows you to show relevant error messages to users based on the context.
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Q.134 How can you handle HTTP errors in Angular 8?
To handle HTTP errors in Angular 8, you can use the catchError operator provided by the rxjs/operators library. By intercepting HTTP responses and checking for errors, you can handle different types of HTTP errors, such as server errors or network errors. You can then customize the error messages and take appropriate actions based on the specific error type.
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Q.135 How can you handle form validation errors in Angular 8?
Angular 8 provides built-in mechanisms for handling form validation errors. You can access form controls and their error states to display validation error messages in the template. By utilizing properties like touched, dirty, and invalid on form controls, you can conditionally display error messages when a form control is in an invalid state.
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Q.136 How can you handle asynchronous errors in Angular 8?
To handle asynchronous errors in Angular 8, you can use the catchError operator along with Observables and Promises. When making asynchronous operations, such as HTTP requests or asynchronous form validations, you can chain the catchError operator to handle any errors that occur during these operations. This allows you to gracefully handle errors and display appropriate error messages to users.
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Q.137 How can you log error messages in Angular 8?
To log error messages in Angular 8, you can use the console.log or console.error methods provided by JavaScript. By strategically placing log statements in your code, you can log error messages to the browser console for debugging and troubleshooting purposes. Additionally, you can integrate logging libraries or services to centralize and manage error logging for better tracking and analysis.
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Q.138 Can you customize error messages based on specific error types in Angular 8?
Yes, you can customize error messages based on specific error types in Angular 8. By implementing conditional logic in error handling mechanisms, such as using if statements or switch cases, you can check the type of error and display different error messages accordingly. This allows you to provide specific and meaningful error messages based on the nature of the error.
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Q.139 How can you handle uncaught errors in Angular 8?
To handle uncaught errors in Angular 8, you can utilize the window.onerror event or the ErrorHandler interface. By implementing custom error handlers, you can catch unhandled errors that occur within the application and take appropriate actions, such as displaying error messages, logging errors, or gracefully handling the errors to prevent application crashes.
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Q.140 How can you internationalize error messages in Angular 8?
Angular 8 provides built-in support for internationalization.
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Q.141 What is the component lifecycle in Angular 8?
The component lifecycle in Angular 8 refers to the series of events and methods that occur during the lifespan of a component. It consists of several phases, including component creation, rendering, updates, and destruction. Understanding the component lifecycle allows you to perform specific tasks at different stages of a component's life.
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Q.142 What are the different stages of the component lifecycle in Angular 8?
The component lifecycle in Angular 8 consists of several stages: ngOnChanges: This method is called when the component receives input property changes. ngOnInit: This method is called after the component has been initialized and its input properties have been set. ngDoCheck: This method is called during every change detection cycle, allowing you to detect and respond to changes. ngAfterContentInit: This method is called after Angular has projected external content into the component's view. ngAfterContentChecked: This method is called after every change detection cycle related to the component's projected content. ngAfterViewInit: This method is called after Angular initializes the component's views and child views. ngAfterViewChecked: This method is called after every change detection cycle related to the component's views. ngOnDestroy: This method is called just before the component is destroyed and removed from the DOM.
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Q.143 How can you utilize the ngOnInit method in Angular 8?
The ngOnInit method is commonly used to perform initialization tasks within a component. It is called after the component has been initialized and its input properties have been set. You can use ngOnInit to fetch data from APIs, initialize variables, subscribe to observables, or perform any other necessary setup tasks before the component is rendered.
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Q.144 How can you utilize the ngDoCheck method in Angular 8?
The ngDoCheck method allows you to perform custom change detection and respond to changes within a component. It is called during every change detection cycle, so you can use it to detect and handle changes that are not automatically detected by Angular's default change detection mechanism. This method is useful for implementing custom change detection logic or optimizing performance by manually checking for changes.
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Q.145 What is the difference between ngAfterContentInit and ngAfterViewInit in Angular 8?
The ngAfterContentInit and ngAfterViewInit methods are both lifecycle hooks in Angular 8, but they are called at different stages of the component lifecycle. ngAfterContentInit is called after Angular has projected external content into the component's view. It is useful when you want to perform tasks that depend on the content projected into the component, such as accessing and manipulating child components or querying the content. ngAfterViewInit is called after Angular initializes the component's views and child views. It is useful when you want to perform tasks that require access to the component's view and its child views, such as accessing DOM elements or interacting with child components.
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Q.146 How can you utilize the ngOnDestroy method in Angular 8?
The ngOnDestroy method is called just before a component is destroyed and removed from the DOM. It is useful for performing cleanup tasks, such as unsubscribing from subscriptions, releasing resources, or canceling ongoing operations. You can use ngOnDestroy to avoid memory leaks and ensure that resources are properly released when a component is no longer needed.
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Q.147 Can you explain the sequence of lifecycle hooks in Angular 8?
The sequence of lifecycle hooks in Angular 8 is as follows: ngOnChanges (if there are input property changes), ngOnInit, ngDoCheck, ngAfterContentInit, ngAfterContentChecked, ngAfterViewInit, ngAfterViewChecked, ngOnDestroy (when the component is about to be destroyed).
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Q.148 What are directives in Angular 8?
Directives in Angular 8 are a powerful feature that allows you to extend the functionality of HTML elements. They are special attributes that you can add to HTML elements to modify their behavior or appearance. There are three types of directives in Angular 8: component directives, attribute directives, and structural directives.
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Q.149 What is the difference between component directives, attribute directives, and structural directives?
Component directives: These are directives that are associated with a component and are used to create reusable UI components. They have their own templates and logic and can be used as custom HTML elements. Attribute directives: These are directives that change the behavior or appearance of an existing HTML element. They are used as attributes on HTML elements and can modify properties, listen to events, or apply visual transformations. Structural directives: These are directives that change the structure of the DOM by adding, removing, or manipulating elements. They are used as attributes on HTML elements and can control the rendering of elements based on conditions or loop through a collection of elements.
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Q.150 How can you create a custom directive in Angular 8?
To create a custom directive in Angular 8, you need to use the @Directive decorator. This decorator allows you to define the selector and other properties of the directive. You can also specify the host element on which the directive should be applied and define the logic for the directive using the @HostListener and @HostBinding decorators.
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Q.151 How can you apply an attribute directive to an element in Angular 8?
To apply an attribute directive to an element in Angular 8, you can simply add the directive as an attribute on the HTML element. For example, if you have a custom attribute directive called highlight, you can apply it to an element like this:
. The directive will then modify the behavior or appearance of the element as defined in its logic.
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Q.152 How can you pass data to a directive in Angular 8?
You can pass data to a directive in Angular 8 by using directive inputs. In the directive definition, you can define input properties using the @Input decorator. These properties can then be bound to values from the component template using property binding syntax. By passing data to a directive, you can customize its behavior or appearance based on the provided values.
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Q.153 Can you explain the lifecycle hooks available for directives in Angular 8?
Directives in Angular 8 have two lifecycle hooks: ngOnChanges: This hook is called when the inputs of the directive change. It receives a SimpleChanges object that contains information about the previous and current values of the inputs. ngOnDestroy: This hook is called when the directive is about to be destroyed. It allows you to perform cleanup tasks, such as unsubscribing from subscriptions or releasing resources.
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Q.154 What is the difference between a directive and a component in Angular 8?
In Angular 8, a component is a type of directive that has its own template and logic and represents a reusable UI component. It is used as a custom HTML element and can have inputs, outputs, and lifecycle hooks. On the other hand, a directive is a more general concept that includes both components and attribute/structural directives. Attribute and structural directives modify the behavior or appearance of existing HTML elements.
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Q.155 Can a directive have its own template in Angular 8?
No, attribute and structural directives do not have their own templates in Angular 8. They are used to modify the behavior or appearance of existing HTML elements. However, component directives, which are a type of directive, have their own templates and can be used as custom HTML elements.
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Q.156 What are services in Angular 8?
Services in Angular 8 are a way to organize and share code and data across different components in an application. They provide a mechanism for implementing reusable business logic, data manipulation, and communication with external services or APIs. Services are typically used to centralize common functionality and promote code reusability.
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Q.157 How can you create a service in Angular 8?
To create a service in Angular 8, you can use the ng generate service command or manually create a TypeScript file with the .service.ts extension. In the service file, you define a class that implements the desired functionality and injectable behavior by using the @Injectable decorator.
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Q.158 How can you provide a service in Angular 8?
To provide a service in Angular 8, you can use the providedIn property in the @Injectable decorator or specify the service in the providers array of a module. The providedIn property allows you to provide the service at the root level by setting it to 'root', while specifying the service in the providers array allows you to provide it at a specific module or component level.
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Q.159 How can you inject a service into a component in Angular 8?
To inject a service into a component in Angular 8, you can use constructor injection. In the component's constructor, you declare a parameter of the service type and Angular's dependency injection system will automatically inject an instance of the service when the component is created. You can then use the injected service instance within the component.
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Q.160 What is the purpose of dependency injection in Angular 8 services?
Dependency injection is a core concept in Angular 8 that allows you to provide dependencies to a class without explicitly creating instances of those dependencies within the class. In the context of services, dependency injection enables the injection of services into components, facilitating code organization, testability, and reusability. It allows services to be decoupled from the components that use them.
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Q.161 How can you share data between components using a service in Angular 8?
You can share data between components using a service in Angular 8 by defining shared properties or methods in the service and having the components interact with those shared properties or methods. The service acts as a central point for storing and managing shared data, allowing multiple components to access and update it.
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Q.162 How can you handle asynchronous operations in Angular 8 services?
In Angular 8 services, you can handle asynchronous operations using Observables or Promises. Observables are streams of values that allow you to handle asynchronous data flows and perform operations such as mapping, filtering, and subscribing. Promises, on the other hand, represent the eventual completion or failure of an asynchronous operation and provide a more simplified approach for handling single async operations.
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Q.163 Can you explain the difference between a service and a component in Angular 8?
In Angular 8, a service is a class that provides functionality and data sharing across components. It is used to implement reusable business logic, data manipulation, and communication with external services. A component, on the other hand, is responsible for the presentation and interaction of the user interface. Components handle user events, display data, and interact with services to perform actions.
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Q.164 How can you handle HTTP requests in an Angular 8 service?
To handle HTTP requests in an Angular 8 service, you can use the HttpClient module provided by Angular. The HttpClient module offers methods to perform various types of HTTP requests, such as GET, POST, PUT, DELETE, etc. You can use these methods in your service to interact with APIs, send data, and receive responses.
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Q.165 What is Dependency Injection (DI) in Angular 8?
Dependency Injection in Angular 8 is a design pattern and a core concept that allows you to create and manage dependencies between different components, services, and modules in an application. It provides a way to pass the required dependencies into a class from an external source, rather than having the class create or manage those dependencies itself.
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Q.166 How does Dependency Injection work in Angular 8?
In Angular 8, the Dependency Injection system is responsible for creating instances of classes and resolving their dependencies. When a class requests a dependency, Angular's DI system looks for a provider that can fulfill that dependency and provides an instance of the requested dependency to the class. This process is automatic and allows for loose coupling and modular design.
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Q.167 What are the benefits of using Dependency Injection in Angular 8?
Using Dependency Injection in Angular 8 offers several benefits: Promotes modularity and code reusability. Facilitates unit testing by allowing easy mocking and substitution of dependencies. Simplifies the management of dependencies by centralizing it within Angular's DI system. Enables loose coupling between classes, making code more maintainable and easier to refactor. Supports scalability and flexibility by easily replacing or extending dependencies.
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Q.168 How can you inject dependencies into a component in Angular 8?
To inject dependencies into a component in Angular 8, you can use constructor injection. In the component's constructor, you declare a parameter of the required dependency type, and Angular's DI system automatically provides an instance of that dependency when the component is created. The DI system uses the provider configuration to determine which instance to provide.
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Q.169 How can you provide dependencies at the module level in Angular 8?
To provide dependencies at the module level in Angular 8, you can use the providers property in the module's metadata. By adding a provider to the providers array, you make the dependency available for injection throughout the module. This ensures that the same instance of the dependency is used across all components within the module.
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Q.170 Can you explain the hierarchical nature of Dependency Injection in Angular 8?
In Angular 8, the Dependency Injection system follows a hierarchical structure. At the root level, there is a root injector that provides dependencies across the entire application. Each component or module can have its own injector, which is a child of the parent injector. When a dependency is requested, Angular's DI system checks the current injector and then recursively moves up the hierarchy until it finds a provider or reaches the root injector.
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Q.171 How can you create custom providers for Dependency Injection in Angular 8?
You can create custom providers for Dependency Injection in Angular 8 by using the providers array in a module or component metadata. A provider can be configured with a specific token and can be instantiated using a class, a value, or a factory function. Custom providers allow you to define how dependencies are resolved and instantiated within your application.
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Q.172 What is the difference between a provider and a service in Angular 8?
In Angular 8, a provider is a configuration object that tells Angular how to create and provide a dependency when requested. A service, on the other hand, is a class that provides specific functionality or data within an application. While a service can be a provider, not all providers are services. Providers can also include other types, such as factories or values, that are used to satisfy dependencies.
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Q.173 What is routing in Angular 8?
Routing in Angular 8 refers to the mechanism of navigating between different components and views in a single-page application (SPA). It allows users to move from one page to another without a full-page refresh, providing a seamless and interactive user experience.
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Q.174 How can you set up routing in Angular 8?
To set up routing in Angular 8, you need to define the routes in the app-routing.module.ts file. In this file, you import the necessary Angular modules, define the routes using the Routes array, and configure the routes with their corresponding components. Finally, you export the configured RouterModule and import it in the root module of your application.
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Q.175 What is the purpose of the RouterOutlet directive in Angular 8?
The RouterOutlet directive in Angular 8 is used as a placeholder in the component's template where the routed components will be displayed. It acts as a container for dynamically loading components based on the current route. The RouterOutlet directive is typically used in the main layout component of the application.
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Q.176 How can you navigate to a different route programmatically in Angular 8?
In Angular 8, you can navigate to a different route programmatically by using the Router service. Inject the Router service in the component where you want to perform the navigation, and then use its navigate method, passing in the desired route path or route URL. You can also include route parameters or query parameters as needed.
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Q.177 What is lazy loading in Angular 8 routing?
Lazy loading is a technique in Angular 8 routing that allows you to load modules and their associated components only when they are needed. Instead of loading all the components upfront, lazy loading splits the application into smaller chunks, loading them on-demand. This improves the initial loading time and optimizes the performance of the application.
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Q.178 How can you implement lazy loading in Angular 8 routing?
To implement lazy loading in Angular 8 routing, you need to create a separate module for each lazy-loaded feature or section of your application. In the route configuration, you specify the path and the corresponding module using the loadChildren property. This tells Angular to load the module and its associated components lazily when the route is accessed.
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Q.179 How can you pass route parameters in Angular 8?
You can pass route parameters in Angular 8 by defining them in the route configuration using the :parameterName syntax. For example, in the route configuration, you can specify a route like path: 'users/:id' to capture the value of the id parameter. To access the parameter value in the component, you can use the ActivatedRoute service.
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Q.180 What are route guards in Angular 8?
Route guards in Angular 8 are used to protect routes and control access to certain parts of an application. They allow you to perform checks and validations before allowing a user to navigate to a specific route. Route guards can be used to implement authentication, authorization, and other custom checks to ensure that the user has the necessary permissions to access a route.
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Q.181 How can you implement route guards in Angular 8?
To implement route guards in Angular 8, you can create a class that implements the CanActivate interface or other related interfaces (CanDeactivate, CanLoad, etc.). In the guard class, you define the logic to check if the user is allowed to activate, deactivate, or load a particular route. You then configure the guard in the route configuration by specifying it in the canActivate, canDeactivate, or canLoad properties.
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Q.182 What are Observables in Angular 8?
Observables in Angular 8 are a powerful data handling mechanism that allows you to work with asynchronous data streams. They are part of the RxJS library and provide a way to handle events, data responses from HTTP requests, and other asynchronous operations in a reactive and efficient manner.
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Q.183 How can you create an Observable in Angular 8?
You can create an Observable in Angular 8 using the Observable class provided by RxJS. The Observable constructor takes a function as an argument, which defines the behavior of the Observable. Within this function, you can emit values using the next method, handle errors using the error method, and complete the Observable using the complete method.
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Q.184 What is the difference between an Observable and a Promise in Angular 8?
In Angular 8, Observables and Promises are both used to handle asynchronous operations. The main difference is that an Observable is a stream of values that can emit multiple values over time, while a Promise represents a single value that can be resolved or rejected only once. Observables also have more powerful features, such as the ability to cancel subscriptions and handle multiple events.
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Q.185 How can you subscribe to an Observable in Angular 8?
To subscribe to an Observable in Angular 8, you use the subscribe method provided by the Observable. The subscribe method takes one or more functions as arguments, which define how to handle the emitted values, errors, and the completion of the Observable. By subscribing, you initiate the execution of the Observable and start receiving the emitted values.
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Q.186 What are operators in Observables and how can you use them in Angular 8?
Operators in Observables are functions that allow you to transform, filter, combine, and manipulate the data emitted by an Observable. RxJS provides a wide range of operators that you can use to perform various operations on Observables. To use an operator, you chain it to an Observable using the pipeable syntax, enabling you to apply multiple operators in a chain.
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Q.187 How can you handle errors in Observables in Angular 8?
In Angular 8, you can handle errors in Observables using the catchError operator provided by RxJS. By using the catchError operator, you can intercept errors emitted by an Observable and handle them gracefully. You can provide a fallback value, rethrow the error, or perform any custom error handling logic within the catchError operator.
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Q.188 How can you unsubscribe from an Observable in Angular 8?
Unsubscribing from an Observable is important to prevent memory leaks and unnecessary computations. In Angular 8, you can unsubscribe from an Observable by calling the unsubscribe method on the Subscription object returned by the subscribe method. Alternatively, you can use higher-order operators like takeUntil to automatically unsubscribe when a specific condition is met.
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Q.189 How can you handle multiple Observables in parallel or sequentially in Angular 8?
To handle multiple Observables in parallel or sequentially in Angular 8, you can use operators like forkJoin and concat provided by RxJS. The forkJoin operator allows you to combine multiple Observables and wait for all of them to complete, while the concat operator allows you to execute multiple Observables sequentially, one after the other.
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Q.190 How can you convert an Observable to a Promise in Angular 8?
In Angular 8, you can convert an Observable to a Promise using the toPromise operator provided by RxJS. The toPromise operator converts the Observable sequence into a Promise that resolves with the last emitted value or rejects with an error. You can then use standard Promise syntax to handle the converted Observable.
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Q.191 What is form handling in Angular 8?
Form handling in Angular 8 refers to the process of capturing user input and managing form data within an Angular application. It involves creating and validating forms, handling form submission, and managing form state.
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Q.192 How can you create a form in Angular 8?
In Angular 8, you can create a form by using the FormsModule or ReactiveFormsModule from @angular/forms package. The FormsModule provides two-way data binding and simplifies form creation, while the ReactiveFormsModule offers a more flexible and powerful approach using reactive form controls.
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Q.193 What is the difference between template-driven forms and reactive forms in Angular 8?
Template-driven forms in Angular 8 rely on directives and two-way data binding to handle form inputs and validation. They are simpler to implement and require less code. On the other hand, reactive forms use explicit form control objects to manage form state, validation, and data flow. They offer more control and flexibility and are recommended for complex forms and dynamic form behaviors.
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Q.194 How can you perform form validation in Angular 8?
Angular 8 provides built-in form validation mechanisms for both template-driven and reactive forms. You can use properties like required, minLength, and pattern on form controls to enforce validation rules. You can also create custom validators by defining functions and applying them to form controls.
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Q.195 How can you handle form submission in Angular 8?
To handle form submission in Angular 8, you can use the (ngSubmit) event binding on the form element. When the form is submitted, the specified method or function is called, allowing you to perform actions such as data processing, making HTTP requests, or navigating to a different route.
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Q.196 How can you access form controls and their values in Angular 8?
In Angular 8, you can access form controls and their values using the FormGroup or FormControl objects. For template-driven forms, you can use the ngModel directive or template reference variables to access form controls. For reactive forms, you can access form controls programmatically by using the get method on the FormGroup or FormControl object.
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Q.197 How can you dynamically add or remove form controls in Angular 8?
To dynamically add or remove form controls in Angular 8, you can use methods provided by the FormArray class, which is part of reactive forms. You can use methods like push to add a control, removeAt to remove a control at a specific index, or clear to remove all controls.
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Q.198 What is form validation in Angular 8 and how can you perform custom validation?
Form validation in Angular 8 ensures that user inputs meet certain criteria or rules. You can perform custom validation by creating a validator function and applying it to form controls. The validator function should return an object with validation errors if the validation fails, or null if the validation succeeds. You can then display validation error messages based on the validation errors.
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Q.199 How can you handle asynchronous form validation in Angular 8?
Asynchronous form validation in Angular 8 involves validating form inputs against remote servers or performing asynchronous operations. You can use the AsyncValidatorFn interface and the async validator provided by the @angular/forms package. The async validator returns a promise or an observable that resolves with validation errors or null.
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Q.200 How can you reset a form in Angular 8?
To reset a form in Angular 8, you can use the reset method provided by the FormGroup or FormControl objects. The reset method clears the form controls' values and resets their states to the default.
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Q.201 What are pipes in Angular 8?
Pipes in Angular 8 are a feature that allows you to transform the output of data in templates. They are used to format, filter, and manipulate data before displaying it to the user. Pipes are represented by the | symbol in Angular templates.
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Q.202 How can you use pipes in Angular 8?
To use a pipe in Angular 8, you apply it to an expression in the template using the | symbol, followed by the pipe name and any optional parameters. For example, you can use the date pipe to format a date value: {{ myDate | date: 'dd/MM/yyyy' }}. The transformed output will be displayed in the template.
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Q.203 What are the built-in pipes in Angular 8?
Angular 8 provides several built-in pipes for common data transformations. Some of the commonly used built-in pipes include uppercase, lowercase, date, currency, decimal, percent, slice, json, and async.
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Q.204 How can you create a custom pipe in Angular 8?
To create a custom pipe in Angular 8, you need to create a new class and implement the PipeTransform interface. The PipeTransform interface requires you to implement the transform method, where you define the logic for transforming the input data. Once the custom pipe is created, you can use it in templates like any other built-in pipe.
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Q.205 How can you pass parameters to a pipe in Angular 8?
In Angular 8, you can pass parameters to a pipe by including them after the pipe name, separated by colons. For example, {{ value | myPipe: param1: param2 }}. Inside the custom pipe class, you can access these parameters in the transform method as additional arguments.
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Q.206 How can you chain multiple pipes together in Angular 8?
You can chain multiple pipes together in Angular 8 by applying them consecutively in the template using the | symbol. The output of one pipe becomes the input for the next pipe. For example, {{ value | pipe1 | pipe2 }}.
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Q.207 What is Angular?

Angular is a JavaScript based framework for developing web and mobile applications. Framework in programming is an abstraction to provide various low levels of functionality by providing functions or libraries. Angular supports single page applications.

Angular is supported by Google and is open source. Angular is popular as it eases efforts and reduces time, to web/ mobile app development. Angular helps in developing a scalable, reliable and user friendly application.

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Q.208 What are the prerequisites for learning Angular?
  • The prerequisites for learning Angular are good knowledge of HTML, CSS and JavaScript, along with a grasp of the HTTP protocol and working of the internet.
  • One should also be conversant with Model View Controller or MVC, Document Object Model or DOM, web page rendering and role of HTML/CSS/JS.
  • As JavaScript is the basis of Angular, exhaustive knowledge of object-oriented programming is a prerequisite for learning Angular.
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Q.209 What is the purpose of Angular?

Learning Angular helps you to easily build single page applications. Angular helps in developing web and mobile applications. Angular helps in developing a scalable, reliable and user friendly application.

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Q.210 How to learn Angular?

Learning Angular is simple, first learn the basics of

  • HTML
  • CSS
  • JavaScript

 

After completing the above, focus on learning and getting conversant with Model View Controller or MVC and Document Object Model or DOM.

 

After getting grasp of above web technologies, opt for Vskills certification on Angular 8, at link - https://www.vskills.in/certification/web-development/angular-8-certification-course

 

Vskills offers following deliverables

-              Online video based, e-learning LMS

-              Hard copy to candidates residing in India

-              Practice tests for assessing your knowledge

-              Government certification

-              Alumni working in software companies like TCS, Accenture, IBM, etc

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Q.211 Where can I learn Angular?

You can learn Angular at Vskills by registering at link - https://www.vskills.in/certification/web-development/angular-8-certification-course . Vskills provides video based learning for Angular 8 with examples to illustrate the concept.

 

Vskills offers following deliverables

-              Online video based, e-learning LMS

-              Hard copy to candidates residing in India

-              Practice tests for assessing your knowledge

-              Government certification

-              Alumni working in software companies like TCS, Accenture, IBM, etc

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Q.212 Which is best to learn; Angular or React?

Angular is best to learn as it has got increasing market share. Feature wise as well, Angular scores more as compared to React in many ways though it may lack in some.

To learn Angular, go for Vskills Angular 8 course for good grasp of latest version of Angular, at link - https://www.vskills.in/certification/web-development/angular-8-certification-course

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Q.213 Which framework should I learn first; Angular vs React vs Vue?

Learn first Angular, as Angular has wide acceptance across industry and has gained huge momentum in short time.


You should opt for Vskills Angular 8 course for good grasp of latest version of Angular, at link - https://www.vskills.in/certification/web-development/angular-8-certification-course

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Q.214 Is there any certification for angular?

Yes, Vskills offers certification on all versions of Angular as

AngularJS - https://www.vskills.in/certification/web-development/certified-angular-js-developer

Angular 2 - https://www.vskills.in/certification/web-development/angular-2-developer-certification

Angular 4 - https://www.vskills.in/certification/web-development/angular-4-certification

Angular 6 - https://www.vskills.in/certification/web-development/angular-6-developer

Angular 8 - https://www.vskills.in/certification/web-development/angular-8-certification-course

 

Vskills certification offers following deliverables, which is not provided by others -

-              Online video based, e-learning LMS

-              Hard copy to candidates residing in India

-              Practice tests for assessing your knowledge

-              Government certification

-              Alumni working in software companies like TCS, Accenture, IBM, etc

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Q.215 What AngularJS 8?

AngularJS 8 is not correct and correct name is Angular 8.

Angular is a JavaScript based framework for developing web and mobile applications. Framework in programming is an abstraction to provide various low levels of functionality by providing functions or libraries. Angular supports single page applications

Angular is supported by Google and is open source. Angular is popular as it eases efforts and reduces time, to web/ mobile app development. Angular helps in developing a scalable, reliable and user friendly application.

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Q.216 Where can I learn AngularJS?

You can learn AngularJS at link - https://www.vskills.in/certification/web-development/certified-angular-js-developer

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Q.217 What is the angular CLI?

The term CLI, expands to Command Line Interface hence, Angular expands to Angular Command Line Interface.

 

Angular CLI or Command Line Interface, is command line or command tool for creation/updation of Angular apps. Angular-cli makes it easy in Angular development by giving boilerplates to save time and resources in development.

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Q.218 Can I learn angular without knowing JavaScript?

No, you cannot learn angular without knowing JavaScript as Angular is based on JavaScript and makes use of JavaScript for its usage or development using Angular.

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Q.219 Is AngularJS hard to learn?

No, AngularJS is not hard to learn but it requires focus in grasping its concepts and techniques.

You should opt for Vskills Angular 8 course for good grasp of latest version of Angular at link - https://www.vskills.in/certification/web-development/angular-8-certification-course

Vskills gives access to video based learning for anytime, anywhere learning with easy to grasp examples.

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Q.220 What is angular training?

Angular training means getting trained in Angular.

Vskills has angular training for all angular versions by giving you video based learning for anytime, anywhere learning with easy to grasp examples.

Angular training links are as -

AngularJS - https://www.vskills.in/certification/web-development/certified-angular-js-developer

Angular 2 - https://www.vskills.in/certification/web-development/angular-2-developer-certification

Angular 4 - https://www.vskills.in/certification/web-development/angular-4-certification

Angular 6 - https://www.vskills.in/certification/web-development/angular-6-developer

Angular 8 - https://www.vskills.in/certification/web-development/angular-8-certification-course

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Q.221 What is angular material design?

Angular material design is the guidelines for using the Angular material user interface or UI library, to develop consistent and functional web or mobile applications.

Angular material design lists guidelines to be followed and Angular material provides various configuration options for the user interface.

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Q.222 What is AngularJS framework?

AngularJS framework is JavaScript based framework for developing web and mobile applications. AngularJS framework extends HTML. AngularJS framework provides a template language similar to HTML, for providing various functionalities for easy and ready to use development.

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Q.223 What is the best way to learn Angular JS?

The best way to learn Angular JS is to first be conversant with basics i.e. working of HTTP, DOM, MVC and OO-programming. Then be conversant in HTML, CSS and JavaScript.

After that register for Vskills Angular JS certification at link - https://www.vskills.in/certification/web-development/certified-angular-js-developer

Vskills  gives video based learning for anytime, anywhere learning with easy to grasp examples.

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Q.224 What is the angular latest version?

Angular latest version is given by Angular Team at Google.

The latest Angular version is Angular 8 which was released on 28 May, 2019.

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Q.225 What is angular and why angular?

Angular is a JavaScript based framework for developing web and mobile applications. Framework in programming is an abstraction to provide various low levels of functionality by providing functions or libraries. Angular supports single page applications.

Why angular, Angular eases efforts and reduces time, to web/ mobile app development. Angular is supported by Google and is open source. Angular helps in developing a scalable, reliable and user friendly application.

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Q.226 What is angular programming?

Angular programming means developing angular based applications.

You should be conversant in Angular for Angular programming.

Vskills gives angular training for all angular versions by giving you video based learning for anytime, anywhere learning with easy to grasp examples.

Angular training links are as -

AngularJS - https://www.vskills.in/certification/web-development/certified-angular-js-developer

Angular 2 - https://www.vskills.in/certification/web-development/angular-2-developer-certification

Angular 4 - https://www.vskills.in/certification/web-development/angular-4-certification

Angular 6 - https://www.vskills.in/certification/web-development/angular-6-developer

Angular 8 - https://www.vskills.in/certification/web-development/angular-8-certification-course

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Q.227 Is angular 8 released?

Yes, Angular 8 was released on 28 May, 2019.

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Q.228 Is angular difficult?

No, angular is not difficult. If you have good knowledge of following, you will quickly get to know Angular -

  • HTML
  • CSS
  • JavaScript
  • DOM
  • MVC
  • HTTP
  • OO programming

 

Vskills gives angular training for all angular versions by giving you video based learning for anytime, anywhere learning with easy to grasp examples.

Angular training links are as -

AngularJS - https://www.vskills.in/certification/web-development/certified-angular-js-developer

Angular 2 - https://www.vskills.in/certification/web-development/angular-2-developer-certification

Angular 4 - https://www.vskills.in/certification/web-development/angular-4-certification

Angular 6 - https://www.vskills.in/certification/web-development/angular-6-developer

Angular 8 - https://www.vskills.in/certification/web-development/angular-8-certification-course

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Q.229 Is there any certification for Angular 8?

Yes, Angular 8 certification is at link - https://www.vskills.in/certification/testing/continuous-testing-certification

Vskills offers following deliverables

-          Online video based, e-learning LMS

-          Hard copy to candidates residing in India

-          Practice tests for assessing your knowledge

-          Government certification

-          Alumni working in software companies like TCS, Accenture, IBM, etc

Report This Question
Q.230

Is there any good link to practice my Angular 8 skills?


Yes, Angular 8 practice test link - https://www.vskills.in/practice/angular-8-questions

Vskills offers following deliverables

-          Online video based, e-learning LMS

-          Hard copy to candidates residing in India

-          Practice tests for assessing your knowledge

-          Government certification

-          Alumni working in software companies like TCS, Accenture, IBM, etc

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