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javascript event handlers

oggiemc asked
Last Modified: 2012-05-11
Can someone explain whats happening in the followong lines of code, taken from the application attached..

var $ = function ( id ) {
return document.getElementById( id );
$("btnDisplay").onclick = display_click;           // In particular, what is going on here??

<title>JavaScript Event Handler</title>
<script type="text/javascript">
// This function receives an id and gets the related XHTML object.
var $ = function ( id ) {
return document.getElementById( id );
var display_click = function () {
alert( "You clicked the button.");
window.onload = function () {
$("btnDisplay").onclick = display_click;
<p><input type="button" value="Display Message" id="btnDisplay" /></p>

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