slide môn học HDJ bài 9 the browser objects in javascript

Web Page Programming with HTML,DHTML & JavaScript/Session 9/ 3 of 21 Event Object - Concept  Events are a result of an action done by the user  An event may be user-generated or genera

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The Browser Objects in JavaScript

Session 9

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Web Page Programming with HTML,DHTML &

JavaScript/Session 9/ 2 of 21

Objectives

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Event Object - Concept

 Events are a result of an action done by the user

 An event may be user-generated or generated by the system

 Each event has an associated event object The event object provides information on:

 the type of event

 the location of the cursor at the time of the event

 The event object is used as a part of an event handler

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Event – Life Cycle

returns

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Handling the Events

 This segment of JavaScript code that will be executed in response to the event is called an event handler

<INPUT TYPE="button"

NAME="docode"

onClick="DoOnClick();">

 Event Handler are categorized as:

 Event handlers for HTML tags

 Event Handlers as Properties

object.eventhandler = function;

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onClick - Example

 The onClick event is generated whenever the user clicks the mouse button on certain form elements or on a hypertext link

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onClick - Output

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onChange - Example

 The onChange event occurs whenever a form element changes This can happen whenever the contents of a text control changes, or when a selection in a selection list changes

} // end hiding from old browsers >

</SCRIPT>

</HEAD>

<FORM>

Please enter a number:

</FORM>

</BODY>

</HTML>

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onChange - Output

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 The onMouseOut event is generated whenever the mouse cursor

moves off of an element

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onMouseOut -Output

 On moving the mouse over Aptech, the following output

is displayed

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onLoad - onSubmit onMouseDown - onMouseUp

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onResize - Example

 This event is activated when a resize event occurs That is,

when a user or script resizes a window or frame

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 An object can be defined as a single entity, consisting of

Properties and Methods

 A property is a value that belongs to an object

Eg: Document.bgcolor

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Window Object

Attribute Value Description (IE)

toolbar Boolean Back , Forward, other buttons in that row, and Address

field, displaying the current URL location Boolean N/A (always defaults to the value of toolbar)

status Boolean Status bar at the bottom of the window

menubar Boolean Menu bar at the top of the window (File, Edit, View, Go,

etc.) scrollbars Boolean N/A (always defaults to “yes”)

resizable Boolean N/A (always defaults to “yes”)

width Pixels Window’s width in pixels

height Pixels Window’s height in pixels

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Document Object

 It represents the HTML document in a given browser window

and is used to retrieve information about the document

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History Object

 This object provides a list of the URL's most recently

visited by the client

 Example, history's "back()" method cause the

window to again display the immediately previous

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Location Object

 This object maintains information about the current URL It

provides a method that causes the window's current URL to be

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Navigator Object

 The navigator object does not belong to JavaScript’s bulk of browser objects It is an independent object, just like the Math object This object combines various methods and properties providing information related to the user’s software

 For example, you can use this object to detect the user’s browser, platform, plug-ins, and many other essential pieces of information.

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