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Events

JavaScript is an event-driven system:

Nothing happens unless it is initiated by an event outside the script.
Browser triggers the event
we have seen the onLoad and onUnLoad events already.

What is an Event?

An event is any change that the user makes to the state of the browser.

JavaScript Events:

Event Description

blur Input focus is moved from the object.

Usually when moving from a field of a form

or from the form itself.

change Value of a field in a form has been

changed by the user entering

or deleting data.

click Mouse is clicked over an

element of a page.

focus Input focus is given to an element.

The reverse of blur.

load Page is loaded by the browser.

mouseover Mouse pointer is moved over an element.

select A field on a form is selected by clicking

the mouse or tabbing from the keyboard.

submit When a form is submitted

(the submit button is clicked).

unload User leaves the Web page.

Event	Description
blur	Input focus is moved from the object.
	Usually when moving from a field of a form
	or from the form itself.
change	Value of a field in a form has been
	changed by the user entering
	or deleting data.
click	Mouse is clicked over an
	element of a page.
focus	Input focus is given to an element.
	The reverse of blur.
load	Page is loaded by the browser.
mouseover	Mouse pointer is moved over an element.
select	A field on a form is selected by clicking
	the mouse or tabbing from the keyboard.
submit	When a form is submitted
	(the submit button is clicked).
unload	User leaves the Web page.

JavaScript Event Handlers

The processing associated with an event is managed by an event handler. The list of event handlers is:

onBlur

onChange

onClick

onFocus

onLoad

onMouseover

onSelect

onSubmit

onUnload

As we have already seen:

These are associated with an HTML element as part of its definition in the HTML source code:

<element attributes event ="handler ">

The handler will be a JavaScript function that you've defined elsewhere and which is available to the element.

For Example:

<body onLoad="init()">

Next: Objects in JavaScript Up: JavaScript: Formal Syntax Previous: Some Useful JavaScript Functions

Dave Marshall
9/28/2001