How to handle local fallbacks?

[tauren]

I am currently loading resources like jquery from google's CDN, but I have a fallback mechanism in place in case the CDN is unavailable:

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js"></script>
<script>window.jQuery || document.write('<script src="js/libs/jquery-1.6.1.min.js">\x3C/script>')</script>

What would be the best way to accomplish this using $script? How is an action taken if a resource does not get loaded? Or what if the jquery.min.js file does get loaded, but for some reason it is empty or corrupt and doesn't define window.jQuery?

[ded]

function ready(fn) {
  $script('//ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js', function () {
    window.jQuery ? fn() : $script('js/libs/jquery-1.6.1.min.js', fn)
  })
}

[tauren]

@ded - thanks for your answer, but could you explain a few things to me?

1. What is the reason you wrapped it in the ready(fn) function? How is ready(fn) used?
2. I assume fn would contain the code to execute once jquery is loaded. Is that correct?
3. Doesn't $script take up to 3 params? The first is the resource/resources, the second is a function to run when all resources are loaded, and the third is a function to run if some resources didn't load. Your code just calls the second parameter, but how does that get called if the script isn't loaded from googleapis? It seems like the third parameter should be used as well.

[ded]

$script takes 3 args. the 2nd being an optional name. if the 2nd is used, then you have another chance to pass in a function as the 3rd.

$script.ready takes 3 args as well. the third being "which deps were not found" (eg: had no name).

regardless of each of those, the $script callback will return if it's found, or errors.