javascript null error

[Millay]

Hello peeps,

Yeasterday I posted about my near identical ubuntu servers and a strange charecter encoding problem.. well today I am having a javascript error that occurs on my live server and not on the local server... everything works fine on the local server, but on the remote server it falls over and Firebug reports the following:

document.getElementById("modelId") is null

the code that is returning this is:

var modelId = document.getElementById('modelId').value;

so i tried this:

	if (document.getElementById('modelId').value == null) {
		var modelId = 1
	}else{
		var modelId = document.getElementById('modelId').value;
	}

to no avail...

If anyone could help i would ve really apreciateive!

[Graham M]

But the PHP Pre-processor shouldn't be touching any of the code so I don't see how that would make sense?

[Millay]

Sorry graham excuse my ignorance, but i cant see how php pre-processor is involved??

[Graham M]

Well you say it works fine on one server and not on another, is the extension of the file .php or?

[Millay]

sorry yes it is a php file so yes it is going through the php preprocessor, which makes me wonder if it has something to do with:

<script language="javascript">populatevanModels('<?php echo $_POST['modelId']; ?>');</script>
<script language="javascript">setTimeout("populatevanDerivatives('<?php echo $_POST['derivativeId']; ?>')",500);</script>

but the strange thing is only the servers have changed al lthe data and backend databases are the same..

[dev]

are you running the js before or after the DOM has fully loaded?

[OldGeezer]

Not really a webby person, so I can't help with why it works on one server but not the other, but shouldn't your code work-around be:

	if (document.getElementById('modelId') == null) {
		var modelId = 1
	}else{
		var modelId = document.getElementById('modelId').value;
	}

[Graham M]

Also try a semi-colon after var modelId = 1

[Paddy1]

Check that document itself isn't null...

var modelId = null;

if (document != null) {
if (document.getElementById('modelId') == null) {
modelId = 1;
}else{
modelId = document.getElementById('modelId').value;
}
} else {
modelId = 1;
}

[Millay]

Im almost out of ideas, i tried all your tips, still to know joy.. any ideas greatly apreciated.

[Graham M]

Could you paste the rest of the code where the modelID input is Millay>

[Millay]

Hi graham and everyone else who helped.

I fixed the problem, it was caused by php code, and some ajax stuff.

I feel silly for posting but apreciate all the help..

Its one of those things you work for 20+ hours straight and you cant see the wood for the trees!

---------- Post added at 22:19 ---------- Previous post was at 22:16 ----------

New we should have used a CVS system..