Find Missing Javascript Includes in Website

Question

Say I have several JavaScript includes in a page:

<script type="text/javascript" src="/js/script0.js"></script>
<script type="text/javascript" src="/js/script1.js"></script>
<script type="text/javascript" src="/js/script2.js"></script>
<script type="text/javascript" src="/js/script3.js"></script>
<script type="text/javascript" src="/js/script4.js"></script>

Is there a way i can tell if any of those weren't found (404) without having to manually check each one? I guess i'm looking for an online tool or something similar. Any ideas?

Answer 1

If you get the Firebug firefox plugin and enable the consoles it should tell you when there are errors retrieving resources in the console.

Answer 2

I don't use other browsers enough to know where to find a similar feature in them, but Safari has an Activity window that displays all of the included files for a given web page and which ones were unable to be retrieved.

Answer 3

If you want to monitor on the fly without actually checking if it exists, then I suggest placing dynamic variables inside the files. Then just do something like this:

var script0Exists = true; // inside script0.js
var script1Exists = true; // inside script1.js

Then in your other files, just use:

if ( script0Exists ) {
    // not a 404 - it exists
}

Answer 4

Log your 404's.

Answer 5

If you don't want to check it manually on the client you will need to do this server-side. You need to make sure whichever webserver you are using is configured to log 404s and then check that log to see which HTTP requests have failed.

Answer 6

If your webhost always returns the HTTP result "200 OK", whether the file exists or not (the latter should give a "404 Not Found"), the browser has no way of telling if it received a script or not.

You might try retrieving the files via XMLHttpRequest, examine the data, and if they look like JS, either eval() them, or create a script tag pointing to the exact same URL you downloaded (if the script is cacheable, it won't be transferred again, as the browser already has it).