Why are my javascript files not loading 'consistently' in IE7?

Question

In what seems to be random occurrences, javascript files are not loading.

I believe this diagnosis is correct because a) I have code to check, b) I've stepped through the code, and c) I get “'myfunction' is undefined” error when functions in those files are used.

Sometimes this doesn’t happen for an hour, sometimes it happens every time I load the page, sometimes it happens every other time I load the page. It seems like every time I identify a consistent behavior so I can repeat it and diagnose it, it changes!

Does anybody have any idea what might be causing this?

I'm using :

• IE version 7.0.5730.11 (had & uninstalled IE8 Beta)
• VS2008

Right now, it appears to only be happening to my colleague and I on our development environments.

There is one script which appears to be missing more than any other. Here's the script tag.

<script language="javascript" 
        type="text/javascript" 
        src="js/Ajax.Utility.js?<%= ConfigurationManager.AppSettings["WebApp.JavaScript.FileVersion"].ToString() %>"></script>

Which evaluates to

<script language="javascript" 
        type="text/javascript" 
        src="js/Ajax.Utility.js?090324a"></script>

The version query string parameter doesn't appear to have any effect either since I've both had and not had the problem immediately after changing it.

Answer 1

Most browsers seem tolerant to additional commas, e.g. in a definition of a list of object properties:

var obj = {prop1: 'value',
           prop2: 'value',};

Internet Explorer is not tolerant to the final comma. Whenever I've had this problem it's ALWAYS proved to be due to an additional comma. Moreover the IE debugger doesn't flag the source problem, it just decries the missing definition(s) from the file that hasn't loaded properly.