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DoubleTakeScript loader. This is a simple way to load a local copy of a library as a fallback to an external CDN.
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Double Take Script Loader

Double Take Script Loader

This is a simple way to load a local copy of a library as a fallback to an external CDN.


But CDNs are awesome!?

Yes they are. There are actually some people who believe you should not use CDNs. If you do decide to use a CDN, you should know that they can fail (unlikely) or be blocked for certain countries (rare, but possible). If a CDN fails and your site depends on that libary, then your site could really suffer and your bounce rate will go to infinity and beyond!

How do I use this?

There are two ways to use this:

1. Call DoubleTakeScriptLoader: Call directly with an array of objects (or a single object) like so:

    propName: '$', //Name of global object which would be loaded if the library loaded correctly
    localSource: 'js/jquery-1.10.2.min.js', //Location of local copy. What src would be if you're not using a CDN
    originalId: 'jQueryScript' //Optional: An id you give to the original script tag. Used to remove the old script tag.
  { ... }

2. Add data attributes: Add data-prop-name and data-local-src to script tags you wish to do a double take on. Like so:

<script src="" data-prop-name="_" data-local-src="underscore-min.js"></script>

With either method, you must add a script tag for the dt-script-loader.js file after the library script tags, but before you use the libraries.

Other info

Note: dt-script-loader.js immediate calls DoubleTakeScriptLoader() with no arguments which will search the DOM for script tags which have the necessary data attributes. If this is a problem, just use method 2 (calling it directly). Or heck, it's not some sort of big library or anything, just remove the invocation yourself.


I developed this quickly one Saturday afternoon. I imagine there could be some improvement to performance or something here. Feel free to leave comments to that effect :)

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