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[SOLVED] document.getElementById(" ") is null issue.


ann
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Hi,

 

I want the contents of a text box to change with the selection from a dropdown menu.  The script below works, but only if I include the line marked <!--why do I need this-->.  If I delete this line the page loads without error but I get document.getElementById("divSCO0") is null when I make a selection and no changing text.

 

How can I get the script to work without the <!--why do I need this--> line?

or

Can I get divXXX not to display? I've got style="display:none" but it still shows!

 

The number of select options and divs  will vary with database content.  Could the java script be written before I have the results of the database query? I guess I'd have to pass it both the total number of options and which option to display?

 

Thanks for your time.

 

<html>
<head>
<script type="text/javascript">
function checker(what){
	document.getElementById("divSCO0").style.display = "none";
	document.getElementById("divSCO1").style.display = "none";
	document.getElementById("divSCO2").style.display = "none";
if (what==1) {
	document.getElementById("divSCO1").style.display = "block";
}else if (what==2) {
	document.getElementById("divSCO2").style.display = "block";
}else {
	document.getElementById("divSCO0").style.display = "block";
}
} 
</script>
</head>

<body>

Select 
<select name="DDselect" onchange="checker(this.value)"><option value="0" selected></option>
<option value="1">1</option>
<option value="2">2</option>

<br><br>

<div id="divXXX" style="display:none"><textarea name="XXX" id="XXX" rows="0" cols="0"></textarea></div><!--why do I need this-->
<div id="divSCO0" style="display:block"><textarea name="SCO0" id="SCO0" rows="2" cols="30"></textarea></div>
<div id="divSCO1" style="display:none"><textarea name="SCO1" id="SCO1" rows="2" cols="30">Selection one from the dropdown</textarea></div>
<div id="divSCO2" style="display:none"><textarea name="SCO2" id="SCO2" rows="2" cols="30">Two selected</textarea></div>

</body>
</html>

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Update

 

I can get rid of the unwanted text box by changing the line to...

<div id="divXXX" style="display:none"><input type=hidden></div><!--why do I need this-->

 

But if you know the 'proper' solution to the problem I'd be grateful for the insight.

 

Cheers

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