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If you are pulling your hair out while trying to demo a JSONP call with JSFiddle, don’t bother. It won’t work out of the box.

There is no doubt that JSFiddle is a super-useful tool for saving little demos that you can share with others.  I use it like crazy when providing simple demos in this blog. Tons of cool features and in general, a brilliant idea.

One little quirk I ran into this morning is JSONP calls. I’m writing Part II of a post called: “Complex Multiple Script Loading Using the jQuery.when() Method and the jQuery.Deferred Object”. In this second part, I introduce the tricky scenario of adding a JSONP call as a dependency, which is in addition to other dependencies that are multiple asynchronous  JavaScript calls that may (or may not) have already loaded in the page (I know, I know….. I need to get a life).


When attempting the code in example # 1, I got the following error: “myCallback is not defined”.

Example # 1

My guess is that JSFiddle uses iframes to render your test code. I’ve not made any attempt to look into this further, and I’m sure the answer is likely a call to “parent” or something similar. But just in you are pulling your hair out trying to demo a JSONP call using JSFiddle, hopefully this will save you the 20 minutes of troubleshooting that I just did. It won’t work out of the box (again, probably due to the use of iFrames). When I figure out the answer, I will post it. I’ll try to look into it this weekend.



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