JSONP only working with named callback function

Question

I have gotten JSONP working with an anonymous function but can't get it to work with a named function. This code works (the alert appears with the correct data):

$.getJSON('http://example.com/test.aspx?foo=bar&callback=?',
    function (data) { alert(data.baz) })

However this code does not work (no alert appears):

function dat(data) {
     alert(data.baz)   
}

$.getJSON('http://example.com/test.aspx?foo=bar&callback=dat')

Can you explain why the last code does not work?

EDIT: I took out a non-relevant example

Are you sure the last one does not work? It is actually the same as the first one. — Felix Kling
– Felix Kling, Commented Feb 3, 2011 at 19:33
@Felix, you're right... I tried that example again and now it works, so I took it out of the question... but there is still the remaining one that does not work (which I also tested again to be sure) — JoelFan
– JoelFan, Commented Feb 3, 2011 at 19:39
@BaroqueBobcat, it's right before the getJSON call, which is in <body><form><div><script> — JoelFan
– JoelFan, Commented Feb 3, 2011 at 19:46

Hamish · Accepted Answer · 2011-02-03 19:51:53Z

2

I'm not sure that leaving out the callback is the correct usage (or, at least, I cannot find any documentation that defines what should happen if a callback is not supplied). If you want to use a named function as the callback you can do:

function dat(data) {
    alert(data.baz)   
}

$.getJSON('http://example.com/test.aspx?foo=bar&callback=?', dat);

answered Feb 3, 2011 at 19:51

Hamish

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Dave Ward · Accepted Answer · 2011-02-03 19:53:33Z

0

You should be able to meet jQuery half way with something like this:

$.getJSON('http://example.com/test.aspx?foo=bar&callback=?', dat);

answered Feb 3, 2011 at 19:53

Dave Ward

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BaroqueBobcat · Accepted Answer · 2011-02-03 20:03:12Z

0

After looking at jquery's ajax code a bit, I think what you want to do is either do like Dave Ward and Hamish suggest, ie pass in the function. Or, I think you can pass the function's name as a string like this, since it is attached to the window and jquery looks at the type of the callback for determining behavior.

function dat(data) {
    alert(data.baz)   
}

$.getJSON('http://example.com/test.aspx?foo=bar&callback=?', 'dat');

Or, you can use getScript which will add the url as a script tag, which is fine for what you are trying to do.

function dat(data) {
    alert(data.baz)   
}

$.getScript('http://example.com/test.aspx?foo=bar&callback=dat');

answered Feb 3, 2011 at 20:03

BaroqueBobcat

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