Load jquery if its not already loaded and use local version if no connection is available

Question

<script type="text/javascript">
if (typeof jQuery == 'undefined') {
var script = document.createElement('script');
script.type = "text/javascript";
script.src = "http://ajax.googleapis.com/ajax/libs/jquery/1.5.2/jquery.min.js";
document.getElementsByTagName('head')[0].appendChild(script);
}
</script>

Here is my current code. Is there any way to load a local copy of the jquery lib, if script.src = "http://ajax.googleapis.com/ajax/libs/jquery/1.5.2/jquery.min.js" fails? And is this script loaded asynchronous? Or will it freeze the ui thread until loaded?

have a look that this question stackoverflow.com/questions/7718935/load-scripts-asynchronously — bhatanant2
– bhatanant2, Commented Sep 18, 2012 at 10:18

elclanrs · Accepted Answer · 2012-09-18 10:17:23Z

4

You can just do this:

<script src="cdn.jquery.js"></script>
<script>window.jQuery || document.write('<script src="/local/jquery.js"><\/script>')</script>

answered Sep 18, 2012 at 10:17

elclanrs

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9 Comments

Johan Over a year ago

doesnt IE throw an exception when jQuery is undefined?

Johan Over a year ago

My problem is that sometimes jquery is already loaded, regardless of if the user is connected to the internet. Could i add another ||? Something like this:

<script>window.jQuery || document.write('<script src="code.jquery.com/jquery-latest.js"><\/script>||document.write('<script src="/local/jquery.js"><\/script>')</script>

elclanrs Over a year ago

Just load it before that snippet and if it fails then it will load the local version. See my edit.

Johan Over a year ago

But now it will load <script src="cdn.jquery.js"></script> even if another version is already loaded, right?

elclanrs Over a year ago

You mean if the script is loaded in cache?

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