Vue.Js Interview Questions

Checkout Vskills Interview questions with answers in Vue.js to prepare for your next job role. The questions are submitted by professionals to help you to prepare for the Interview.

Q.1 What are Navigation Guards in Vue.js?

Navigation Guards are hooks provided by Vue Router that allow you to control and manage navigation within your Vue.js application. They provide an opportunity to guard routes by executing certain actions before the route is entered, updated, or left.

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Q.2 What are the three types of Navigation Guards available in Vue.js?

The three types of Navigation Guards are: beforeEach, beforeResolve, and afterEach.

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Q.3 What is the purpose of the beforeEach Navigation Guard?

The beforeEach guard is used to perform actions before entering any route. It can be used for tasks like authentication, permission checks, or data loading.

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Q.4 How do you define a beforeEach Navigation Guard?

You can define a beforeEach guard by adding a function to the beforeEach hook of the Vue Router instance. This function receives three arguments: to, from, and next.

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Q.5 What is the purpose of the beforeResolve Navigation Guard?

The beforeResolve guard is similar to beforeEach, but it runs after the route components have been resolved. It is useful for handling asynchronous route components.

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Q.6 How do you define a beforeResolve Navigation Guard?

You can define a beforeResolve guard by adding a function to the beforeResolve hook of the Vue Router instance. This function also receives to, from, and next arguments.

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Q.7 What is the purpose of the afterEach Navigation Guard?

The afterEach guard is executed after a route has been successfully navigated. It is typically used for tasks like logging or analytics.

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Q.8 How do you define an afterEach Navigation Guard?

To define an afterEach guard, you can add a function to the afterEach hook of the Vue Router instance. The function receives a single argument: to.

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Q.9 How can you cancel a navigation in a Navigation Guard?

To cancel a navigation in a Navigation Guard, you can call the next function with an argument of false.

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Q.10 How can you redirect to a different route in a Navigation Guard?

To redirect to a different route in a Navigation Guard, you can call the next function with the desired route's path or object.

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Q.11 What is Lazy Loading in Vue.js routing?

Lazy Loading in Vue.js routing is a technique used to load route components only when they are needed, rather than loading all components upfront. It helps improve the initial loading time and reduces the bundle size of the application.

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Q.12 How do you enable Lazy Loading for routes in Vue.js?

To enable Lazy Loading for routes in Vue.js, you can use dynamic import syntax and configure your routes accordingly. For example: { path: '/example', component: () => import('./Example.vue') }.

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Q.13 What is the benefit of using Lazy Loading for routes?

The main benefit of Lazy Loading routes is improved performance. By loading route components on demand, the initial bundle size is reduced, resulting in faster page load times. It also helps optimize the overall application loading time.

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Q.14 How can you verify if Lazy Loading is working for a route?

To verify if Lazy Loading is working for a route, you can check the network tab in your browser's developer tools. If Lazy Loading is implemented correctly, you should see the route component being loaded separately when navigating to that route.

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Q.15 Can you use Lazy Loading for all routes in your Vue.js application?

Yes, you can use Lazy Loading for all routes in your Vue.js application. By applying Lazy Loading to all routes, you can achieve optimal performance by loading components only when necessary.

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Q.16 What are the considerations when implementing Lazy Loading in Vue.js?

When implementing Lazy Loading in Vue.js, you should consider the granularity of the route components. It's recommended to split your application into smaller, reusable components to take full advantage of Lazy Loading.

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Q.17 How does Lazy Loading affect code splitting and bundle optimization?

Lazy Loading in Vue.js is closely related to code splitting and bundle optimization. It allows the bundler (e.g., webpack) to separate route components into separate chunks, which can be loaded on demand. This helps reduce the initial bundle size and improves performance.

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Q.18 Can you combine Lazy Loading with other Vue Router features, such as Navigation Guards?

Yes, Lazy Loading can be combined with other Vue Router features like Navigation Guards. You can apply Navigation Guards to the lazy-loaded route components to perform actions such as authentication, data fetching, or permission checks.

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Q.19 Are there any potential downsides to using Lazy Loading in Vue.js?

One potential downside of Lazy Loading is the additional network requests required to load route components on demand. However, this is usually outweighed by the benefits of improved performance and reduced initial loading time.

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Q.20 Can Lazy Loading be used in conjunction with Vuex and state management?

Yes, Lazy Loading can be used in conjunction with Vuex and state management. The route components can still access the centralized store managed by Vuex, allowing you to maintain a consistent application state across lazy-loaded routes.

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Q.21 What does it mean to group routes into chunks in Vue.js?

Grouping routes into chunks in Vue.js refers to dividing the route components of an application into separate chunks or bundles. This allows for lazy loading and loading only the necessary components when navigating to specific routes.

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Q.22 How can you group routes into chunks in Vue.js?

You can group routes into chunks in Vue.js by leveraging dynamic import syntax and configuring your routes accordingly. Each route can be associated with a separate chunk, which will be loaded on demand.

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Q.23 What is the advantage of grouping routes into chunks?

The main advantage of grouping routes into chunks is improved performance. By loading route components on demand, you can reduce the initial bundle size, resulting in faster page load times and better overall application performance.

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Q.24 Can you specify a custom chunk name when grouping routes in Vue.js?

Yes, you can specify a custom chunk name when grouping routes in Vue.js. By providing a chunk name during dynamic import, you can control the name of the generated chunk file.

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Q.25 How can you optimize the grouping of routes into chunks?

To optimize the grouping of routes into chunks, you can consider factors such as the size and complexity of the route components. Breaking down large components into smaller, more granular ones can help achieve better optimization and more efficient lazy loading.

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Q.26 What happens when a route component depends on a shared dependency?

When a route component depends on a shared dependency, such as a library or utility module, it is important to ensure that the shared dependency is not duplicated in each chunk. You can use code splitting techniques, such as using webpack's splitChunks configuration, to extract shared dependencies into separate chunks.

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Q.27 Can you have multiple routes share the same chunk in Vue.js?

Yes, multiple routes can share the same chunk in Vue.js. This can be achieved by specifying the same chunk name for the associated route components. When any of the routes are accessed, the shared chunk will be loaded.

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Q.28 How can you test and verify the effectiveness of route chunking in Vue.js?

You can test and verify the effectiveness of route chunking in Vue.js by inspecting the network tab in your browser's developer tools. When navigating to different routes, you should observe the loading of separate chunk files corresponding to each route component.

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Q.29 What considerations should be taken when grouping routes into chunks in large-scale applications?

In large-scale applications, it is important to consider the overall application architecture and structure. Grouping routes into chunks should align with the module or feature-based organization of your application to achieve better code maintainability and scalability.

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Q.30 Can you dynamically change the chunk associated with a route during runtime?

Yes, you can dynamically change the chunk associated with a route during runtime. By using Vue Router's dynamic route matching or programmatically changing the route's component property, you can load a different chunk for a specific route based on certain conditions or user interactions.

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Q.31 What is the Composition API in Vue.js?

The Composition API is a new approach to organizing and reusing logic in Vue.js applications. It allows developers to define reusable logic as functions, making it easier to compose and share code across components.

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Q.32 How does the Composition API differ from the Options API in Vue.js?

The Options API, which was the traditional way of defining components in Vue.js, relies on options objects like data, methods, and computed. In contrast, the Composition API focuses on using functions to encapsulate logic and data.

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Q.33 What are the advantages of using the Composition API?

The Composition API offers several advantages, including improved code organization, better code reuse, increased flexibility in managing component logic, and enhanced TypeScript support.

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Q.34 How do you define a component using the Composition API?

To define a component using the Composition API, you can use the setup() function instead of options like data or methods. The setup() function returns an object containing data, computed properties, and methods to be used in the component.

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Q.35 What is the purpose of the ref function in the Composition API?

The ref function is used to create a reactive reference to a value. It ensures that changes to the value trigger reactivity and updates in the component.

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Q.36 How do you create a reactive property in the Composition API?

You can create a reactive property in the Composition API by using the ref function. For example: const count = ref(0) creates a reactive property named count with an initial value of 0.

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Q.37 What is the difference between ref and reactive in the Composition API?

While ref creates a reactive reference to a single value, reactive allows you to create a reactive object that can contain multiple properties.

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Q.38 How can you access the component's lifecycle hooks in the Composition API?

In the Composition API, you can use the onMounted, onUpdated, and onUnmounted functions to access the corresponding lifecycle hooks of a component.

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Q.39 How do you share logic between components using the Composition API?

To share logic between components, you can extract common code into a separate function or composition function and import it into the components where it's needed.

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Q.40 Can you use the Composition API alongside the Options API in Vue.js?

Yes, you can use the Composition API alongside the Options API in Vue.js. This allows for a gradual adoption of the Composition API in existing projects, where you can choose to use the Composition API for specific components or parts of the application.

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Q.41 What is the purpose of reactive in Vue.js?

The reactive function is used in Vue.js to create a reactive proxy object. It converts an existing object into a reactive one, allowing changes to its properties to trigger reactivity and update the component.

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Q.42 How do you use the reactive function in Vue.js?

To use the reactive function, you pass an object as an argument, and it returns a reactive proxy of that object. For example: const state = reactive({ count: 0 }) creates a reactive state object with a property named count.

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Q.43 What is the benefit of using reactive in Vue.js?

Using reactive in Vue.js enables reactivity on object properties. Any changes made to those properties will trigger updates in the component that is using them, ensuring a consistent and reactive UI.

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Q.44 How does reactivity work with nested objects using reactive in Vue.js?

When using reactive in Vue.js, nested objects within the reactive object will also become reactive. Any changes made to the nested object's properties will trigger reactivity and updates in the component.

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Q.45 What is the purpose of isReactive in Vue.js?

The isReactive function is used to determine whether an object is reactive or not. It returns true if the object is reactive and false otherwise.

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Q.46 How do you use the isReactive function in Vue.js?

To use the isReactive function, you pass an object as an argument, and it returns a Boolean value indicating whether the object is reactive or not. For example: const check = isReactive(state) returns true if the state object is reactive.

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Q.47 Can you use isReactive to check the reactivity of nested objects?

Yes, you can use isReactive to check the reactivity of both the top-level object and nested objects. It will return true if both the top-level object and its nested objects are reactive.

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Q.48 What are some use cases for using isReactive in Vue.js?

Some use cases for using isReactive include debugging and verifying if an object has been converted to a reactive state. It can be helpful in understanding reactivity behavior and identifying potential issues.

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Q.49 Are there any performance considerations when using reactive and isReactive in Vue.js?

While reactive and isReactive are convenient for enabling reactivity, it's important to note that reactivity comes with a performance cost. Reactive objects require tracking and observing changes, so excessive reactivity may impact the overall performance of the application.

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Q.50 Can you combine reactive with other Vue.js features like computed properties and watchers?

Yes, you can combine reactive with other Vue.js features like computed properties and watchers. Computed properties can be derived from reactive objects, and watchers can observe changes in reactive properties, allowing you to react to specific changes in the component.

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Q.51 What is the purpose of the watch function in Vue.js?

The watch function is used in Vue.js to reactively watch for changes in a specific property or expression and perform custom actions when the watched value changes.

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Q.52 How do you use the watch function in Vue.js?

To use the watch function, you provide it with two arguments: the property or expression to watch and a callback function that will be executed when the value changes.

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Q.53 What is the purpose of the watchEffect function in Vue.js?

The watchEffect function is used in Vue.js to create an immediate reactive effect. It automatically runs the provided callback function and tracks its dependencies to trigger reactivity whenever those dependencies change.

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Q.54 How do you use the watchEffect function in Vue.js?

Using the watchEffect function is simple. You provide it with a callback function, and Vue.js will automatically run that function and track its dependencies for reactivity.

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Q.55 What is the difference between watch and watchEffect in Vue.js?

The main difference between watch and watchEffect is that watch allows you to explicitly define the property or expression to watch, while watchEffect automatically detects the dependencies based on the callback function.

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Q.56 Can you specify multiple properties to watch using the watch function in Vue.js?

Yes, you can specify multiple properties to watch using the watch function by passing an array of properties or using an object notation to watch multiple expressions.

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Q.57 How do you stop watching a property or expression using the watch function?

To stop watching a property or expression using the watch function, you can assign the returned watcher instance to a variable and call its stop method when you no longer want to watch the value.

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Q.58 Can you use the watch function to perform asynchronous operations?

Yes, you can use the watch function to perform asynchronous operations. By marking the callback function as async and using await inside it, you can perform asynchronous tasks within the watch callback.

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Q.59 What is the benefit of using watchEffect over watch in Vue.js?

The benefit of using watchEffect over watch is that watchEffect automatically detects the dependencies based on the callback function, making it more concise and less error-prone when you have multiple dependencies.

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Q.60 Can you access the previous and current values of a watched property or expression?

Yes, when using the watch function, the callback function receives two arguments: the new value and the previous value of the watched property or expression. You can access these values to perform custom actions or comparisons.

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Q.61 What is the purpose of the Provide/Inject pattern in Vue.js?

The Provide/Inject pattern in Vue.js allows you to provide data or values in a component and make them available for injection and use in child components, regardless of the component hierarchy.

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Q.62 How do you use the Provide/Inject pattern in Vue.js?

To use the Provide/Inject pattern, you use the provide option in the parent component to provide data or values, and then use the inject option in the child component to access and use those provided values.

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Q.63 What is the advantage of using the Provide/Inject pattern over props or vuex for data sharing?

The Provide/Inject pattern provides a flexible way of sharing data between components that may not have a direct parent-child relationship. It avoids the need for passing data through props or relying on a centralized store like Vuex.

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Q.64 Can you provide and inject multiple values using the Provide/Inject pattern?

Yes, you can provide and inject multiple values using the Provide/Inject pattern. When providing, you can pass an object with multiple properties, and when injecting, you can specify the names of the properties you want to inject.

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Q.65 What happens if a component tries to inject a value that hasn't been provided?

If a component tries to inject a value that hasn't been provided, it will fallback to the default value specified in the inject option. If no default value is provided, it will be undefined.

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Q.66 Can you change the provided value and have it reflected in all the injected components?

Yes, you can change the provided value and have it reflected in all the injected components. The provided value is reactive, so any changes to it will trigger reactivity and update the injected components.

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Q.67 What is the scope of the Provide/Inject pattern?

The Provide/Inject pattern is not limited to direct parent-child relationships. It allows data sharing across multiple levels of nesting and can be used to provide values to any component within the same inject tree.

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Q.68 Can you provide and inject functions or methods using the Provide/Inject pattern?

Yes, you can provide and inject functions or methods using the Provide/Inject pattern. It is not limited to just data sharing; it can also be used for sharing functions or methods between components.

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Q.69 What are the considerations when using the Provide/Inject pattern?

When using the Provide/Inject pattern, it's important to be mindful of the component hierarchy and ensure that the provided values are expected and used appropriately by the injected components. Overusing Provide/Inject may make the codebase harder to understand and maintain.

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Q.70 How does the Provide/Inject pattern differ from the props system?

While the props system is used for passing data from parent to child components, the Provide/Inject pattern allows you to provide and inject data across multiple levels of nesting and without the need for direct parent-child relationships.

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Q.71 What is the purpose of Router Link in Vue.js?

Router Link is a component in Vue.js that provides declarative navigation to different routes in your application. It generates the appropriate anchor tag () with the necessary attributes to handle route changes.

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Q.72 How do you use Router Link in Vue.js?

To use Router Link, you can replace the traditional tags with tags and specify the to attribute with the desired route path. For example: Home.

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Q.73 What is the benefit of using Router Link over plain anchor tags for navigation in Vue.js?

Using Router Link provides several benefits over plain anchor tags. It automatically updates the URL and handles route changes without causing a full page reload. It also applies active class styling when the route matches the current URL, enhancing the user experience.

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Q.74 Can you pass dynamic route parameters with Router Link?

Yes, you can pass dynamic route parameters with Router Link. You can use the to attribute and provide route parameters as part of the path. For example: User Profile.

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Q.75 What is the purpose of Router View in Vue.js?

Router View is a component in Vue.js that acts as a placeholder for the component associated with the current route. It renders the matched component based on the current route configuration.

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Q.76 How do you use Router View in Vue.js?

To use Router View, you need to define it within your Vue.js template where you want the route component to be rendered. Typically, it is placed in the parent component or the layout component where the dynamic content will be displayed.

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Q.77 Can you have multiple Router View components in a Vue.js application?

Yes, you can have multiple Router View components in a Vue.js application. This is useful when you have nested routes or want to render different components based on different sections of your application.

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Q.78 How does Router View determine which component to render?

Router View determines which component to render based on the current route configuration. When the route changes, the Router View component updates and renders the component associated with the new route.

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Q.79 Can you use Router View without Router Link?

Yes, you can use Router View without Router Link. Router View is responsible for rendering the component associated with the current route, whereas Router Link provides a convenient way to navigate between routes.

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Q.80 How does Router Link and Router View work together in a Vue.js application?

Router Link and Router View work together to enable navigation and route component rendering in a Vue.js application. Router Link is used to create clickable links that trigger route changes, while Router View renders the appropriate component based on the current route.

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Q.81 What is prop validation in Vue.js?

Prop validation in Vue.js is the process of defining rules and constraints for the props passed to a component. It helps ensure that the received prop values meet the expected requirements.

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Q.82 How do you perform prop validation in Vue.js?

To perform prop validation in Vue.js, you can define a props option in your component and specify the expected types, default values, and other validation rules for each prop.

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Q.83 What is the benefit of prop validation in Vue.js?

Prop validation provides several benefits, including improved component reliability, clearer communication between parent and child components, and easier debugging by catching potential prop value issues.

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Q.84 What are the different types of prop validation available in Vue.js?

In Vue.js, you can perform prop validation based on various criteria, such as type checking, presence validation, custom validator functions, and more.

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Q.85 How do you specify the data type for a prop in Vue.js prop validation?

To specify the data type for a prop in Vue.js prop validation, you can use the type property in the props option and provide the expected JavaScript constructor or an array of constructors. For example: props: { age: Number }.

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Q.86 Can you provide default values for props in Vue.js?

Yes, you can provide default values for props in Vue.js by using the default property in the props option. The default value will be used if the parent component doesn't provide the prop.

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Q.87 How can you define custom validator functions for props in Vue.js?

To define custom validator functions for props in Vue.js, you can use the validator property in the props option. The validator function receives the prop value as an argument and should return true if the value is valid or an error message if it's not.

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Q.88 What happens if a prop fails validation in Vue.js?

If a prop fails validation in Vue.js, a warning will be logged in the browser's console, indicating the invalid prop value and the expected validation rules.

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Q.89 Is prop validation mandatory in Vue.js?

No, prop validation is not mandatory in Vue.js. It is considered a best practice, but it's optional. However, using prop validation can help improve the robustness and maintainability of your components.

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Q.90 Can you perform prop validation on functional components in Vue.js?

Yes, you can perform prop validation on functional components in Vue.js by using the same prop validation techniques as in regular components. Functional components can also define the props option to validate the props received from the parent component.

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Q.91 What are non-prop attributes in Vue.js?

Non-prop attributes in Vue.js are attributes that are passed to a component but are not explicitly defined as props. These attributes can be accessed and used within the component but are not automatically added to the component's props.

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Q.92 How can you access non-prop attributes in a Vue.js component?

You can access non-prop attributes in a Vue.js component using the $attrs property. This property contains all the non-prop attributes passed to the component.

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Q.93 How are non-prop attributes different from props in Vue.js?

Non-prop attributes are different from props in Vue.js as they are not explicitly declared or defined within the component's props option. They are additional attributes that can be passed to the component and accessed using the $attrs property.

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Q.94 What is the purpose of non-prop attributes in Vue.js?

Non-prop attributes provide a way to pass additional data or configuration to a component without explicitly defining them as props. This allows for more flexibility and extensibility when using components.

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Q.95 Can you bind non-prop attributes to elements or components in Vue.js?

Yes, you can bind non-prop attributes to elements or components in Vue.js using the v-bind or : directive. This allows you to dynamically pass values to non-prop attributes.

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Q.96 How do you forward non-prop attributes to child components in Vue.js?

To forward non-prop attributes to child components in Vue.js, you can use the v-bind="$attrs" directive on the child component. This passes all the non-prop attributes of the parent component to the child component.

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Q.97 Can you modify or add non-prop attributes within a Vue.js component?

Yes, you can modify or add non-prop attributes within a Vue.js component by directly manipulating the $attrs object. However, it's generally recommended to treat non-prop attributes as read-only and avoid modifying them.

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Q.98 What happens to non-prop attributes when using component composition with slots in Vue.js?

When using component composition with slots in Vue.js, non-prop attributes are automatically passed down to the component that renders the slot content. The component can access these attributes using the $attrs property.

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Q.99 How are non-prop attributes used in component libraries or third-party components?

Non-prop attributes are commonly used in component libraries or third-party components to allow users to pass additional attributes to customize the component's behavior or appearance. The library/component can handle these non-prop attributes based on their own implementation.

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Q.100 Can you access non-prop attributes within the scoped CSS of a Vue.js component?

No, non-prop attributes cannot be accessed directly within the scoped CSS of a Vue.js component. Scoped CSS only applies to elements within the component's template and does not have access to non-prop attributes.

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Q.101 What is fallback content in Vue.js?

Fallback content in Vue.js refers to the content that is displayed when a component's slot is empty or not provided by the parent component.

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Q.102 How do you provide fallback content in Vue.js components?

To provide fallback content in Vue.js components, you can use the element with default content between the opening and closing tags of the component. The default content will be displayed when no content is passed to the slot.

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Q.103 Can you have multiple fallback slots in a Vue.js component?

Yes, you can have multiple fallback slots in a Vue.js component. By using named slots, you can define multiple slots in a component and provide different fallback content for each slot.

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Q.104 How can you conditionally render fallback content based on slot usage in Vue.js?

You can conditionally render fallback content based on slot usage in Vue.js by using the v-if directive on the element. This allows you to check if the slot has any content and display different fallback content accordingly.

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Q.105 What is the purpose of the