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javascript simple question

Posted on 2013-01-29
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Last Modified: 2013-01-29
why when I put javascript code into <head> section , it is not working, only when I
put it into body section:

<head>


 /* read jquery etc */

</head>
<body>


<select>
 <option> 1 </option>
 <option> 2 </option>
  
</select>
 
 <script>

	
 $("select").change(function() {

 	 

 	var sel	=	$(this).val();

 	if  (sel != 0 )
 	{
 	 		
	}		

	});  			


</script> 

</body>
</html>

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Question by:sniger
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2 Comments
 
LVL 82

Accepted Solution

by:
leakim971 earned 500 total points
ID: 38833849
When you put it in the body, AFTER the select box, it mean the select is already in the document (because you put it after)
When you put it in the head section, the body is not loaded, no select so you can play with it

You need to be sure document object model is ready to use
http://james.padolsey.com/javascript/some-jquery-shortcuts/
http://www.learningjquery.com/2006/09/introducing-document-ready
http://web.enavu.com/daily-tip/daily-tip-difference-between-document-ready-and-window-load-in-jquery/

<head>


 /* read jquery etc */
 <script>
$(document).ready(function() { // wait the DOM is ready to use
	
 $("select").change(function() {

 	 

 	var sel	=	$(this).val();

 	if  (sel != 0 )
 	{
 	 		
	}		

	});  			

})
</script> 
</head>
<body>
<select>
 <option> 1 </option>
 <option> 2 </option>  
</select>
</body>
</html>

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LVL 21

Expert Comment

by:Tapan Pattanaik
ID: 38833851
Hi  sniger,

JavaScript writes into the HTML <body> while the page loads.

Please check this link.

http://www.w3schools.com/js/js_howto.asp
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