Object Hierarchy and predefined objects

The image below shows the Object Hierarchy:

 

The Object Hierarchy helps determine the right Dot Syntax for relationships between objects as

document.formName.textBoxName.value
It is easy to follow the path to the text object of the form using the object hierarchy shown above.

A table of the most commonly used JavaScript objects with all of their properties, methods and event handlers are listed below:

Object	Properties	Methods	Event Handlers
Window	defaultStatus, frames, opener, parent, scroll, self, status, top, window	Alert, blur, close, confirm, focus, open, prompt,clearTimeout ,setTimeout	onLoad, onUnload, onBlur, onFocus
Frame	defaultStatus, frames, opener, parent, scroll, self, status, top, window	alert, blur, close, confirm, focus, open prompt, clearTimeout, setTimeout	none
Location	hash, host, hostname, href, pathname, por, protocol, search	reload() replace()	none
History	length, forward, go	back	none
Navigator	appCodeName, appName, appVersion, mimeTypes, plugins, userAgent	javaEnabled	none
document	alinkColor, anchors, applets, area, bgColor, cookie, fgColor, forms, images, lastModified, linkColor, links, location, referrer, title, vlinkColor	clear, close, open, write, writeln	none
image	border, complete, height, hspace, lowsrc, name, src, vspace, width	none	none
form	action, elements, encoding, FileUpload, method, name, target	submit, reset	onSubmit, onReset
text	defaultValue, name, type, value	focus, blur, select	onBlur, onCharge, onFocus,onSelect

Predefined Objects – They include Array, Boolean, Date, Function, Math, Number, RegExp, and String.

Array Object – JavaScript does not have an explicit array data type. However, use the predefined Array object and its methods to work with arrays in applications. The Array object has methods for manipulating arrays in various ways, such as joining, reversing, sorting them. It has a property for determining the array length and other properties for use with regular expressions.

Boolean Object – Use the predefined Boolean object to convert a non-boolean value to a boolean value. Use the Boolean object any place JavaScript expects a primitive boolean value. JavaScript returns the primitive value of the Boolean object by automatically invoking the valueOf method.

Date Object – JavaScript does not have a date data type. Use the Date object and its methods to work with dates and times in applications. The Date object has a large number of methods for setting, getting, and manipulating dates. It does not have any properties.

Function Object – The predefined Function object specifies a string of JavaScript code to be compiled as a function.

Number Object – The Number object has properties for numerical constants, such as maximum value, not-a-number, and infinity. The values of these properties cannot be changed.

RegExp Object – The RegExp object enables working with regular expressions.

String Object – JavaScript does not have a string data type. However, use the String object and its methods to work with strings in applications. The String object has a large number of methods for manipulating strings.

Back to Tutorial