Check if javascript file was loaded

Question

I am loading the following javascript files from a CDN. Is there any way I can check if these have been loaded correctly and if not, load them from a local folder?

http://ajax.microsoft.com/ajax/jQuery/jquery-1.4.2.min.js http://ajax.microsoft.com/ajax/jquery.ui/1.8.5/jquery-ui.min.js http://ajax.microsoft.com/ajax/jquery.validate/1.7/jquery.validate.min.js

I know I can check the jquery file but not sure about the others. Any tips?

Rajat · Accepted Answer · 2010-10-27 18:01:34Z

11

In your HTML, you can do something like this:

  <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
  <script>!window.jQuery && document.write('<script src="js/jquery-1.4.2.min.js"><\/script>')</script>

The example shown is loading jquery from Google CDN and falls back on a local copy of JQuery if that fails.

Credits to HTML5 Boilerplate for showing the trick

answered Oct 27, 2010 at 18:01

Rajat

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6 Comments

scottm Over a year ago

For ui and validate, do that same, checking for $.ui or $.validate

amateur Over a year ago

Thanks to both. Scottm - $.ui does the trick in checking if ui javascript is loaded but unfortunately $.validate does not. Any tips as how I check for the validate plugin?

amateur Over a year ago

Anyone have any idea regarding checking if the validate plugin is loaded?

Rajat Over a year ago

I think you can check for existence of jQuery.fn.myPlugin & if it hasn't loaded from the external source, then fetch it from the local copy. So for your case it could be something like : <script>!window.jQuery.fn.validate && document.write('<script src="js/jquery.validate.min.js"><\/script>')</script>

amateur Over a year ago

Is there a quick an easy way to integrate into this https - so that the cdn will change its url to https if the web page is in https?

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Kevin C. · Accepted Answer · 2011-07-22 23:49:35Z

3

YepNope.js is a more robust solution for loading resources (like js files), checking whether they've been loaded or not, and then providing a fallback if necessary. This is just 1 feature among many provided by the library.

answered Jul 22, 2011 at 23:49

Kevin C.

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1 Comment

Hussein Al-Mosawi Over a year ago

This resource link is broken... Can you please, update it?

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