CODEWITHSUNDEEP
javascriptjquery
Muhammad Reda
Muhammad Reda

Reputation: 27043

Execute javascript callback from within "script" tag after loading a javascript file

I want to execute a javscript callback from within the <script> tag after loading a javascript file, using query string callback=MyCallbackFuntion.

Something similar to 

<script src="http://gdata.youtube.com/feeds/users/USER/uploads?
        alt=json-in-script
        &max-results=30
        &callback=listVideosCallback" 
    type="text/javascript"></script>

Here at the end of src=http://..., youtube uses the query string ?callback= listVideosCallback to execute the function listVideosCallback() after the data/file is loaded. How can I do something similar?

Upvotes: 1

Views: 2604

Answers (1)

Barmar
Barmar

Reputation: 781726

Your server script should do something like (this example is PHP):

echo $_GET['callback'] . '(' . json_encode($data) . ');';

What is JSONP all about?

When you use <script src="URL"></script>, the browser downloads the URL, and then executes the Javascript code that it contains. If that code looks like:

MyCallbackFunction(data);

then loading the script will cause the function to be called with the data as a parameter. So the server script should get the function name from the callback URL parameter, and turn it into a function call by putting parentheses and a literal data object after it and echoing this.

Upvotes: 1

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