How to use jQuery .When .done

Question

I'm trying to run one function after another function completes.

 $.when(saveCanvas(canvas)).done(setWallPaper());

Each function works fine on it's own but when I run the code above it only runs the first function.

What do I need to change?

Hard to answer without seeing the actual functions' implementations, but wild guess `$.when(saveCanvas(canvas)).done(setWallPaper);` — Fabrício Matté, Mar 24 '13 at 02:41

score 9 · Answer 1 · edited May 23 '17 at 11:54

9

According to a comment on another SO question, $.when expects deferred objects as arguments. If you don't pass anything, the callbacks will be invoked immediately.

Does setWallPaper() appear to not be working because it is actually being run before saveCancas(canvas)? saveCanvas() is not actually a deferred object, which when expects it to be. To make it a deferred object, add dfr = $.Deferred(); to the beginning of your saveCanvas() function and return dfr.promise(); to the end of it. Check out this SO answer for more details.

function saveCanvas(canvas)
{
    dfr = $.Deferred();
    //Your code
    return dfr.promise();
}

Read more: http://api.jquery.com/jQuery.when/

edited May 23 '17 at 11:54

Community

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answered Mar 24 '13 at 02:46

Luke Shaheen

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You're right about it running immediately but passing in canvas didn't seem to have an effect. – Philip Kirkbride Mar 24 '13 at 02:54
@PhilipK Edited my answer to suggest a different solution – Luke Shaheen Mar 24 '13 at 03:01
Remember that the promise must be resolved at some point, or the done callback will never fire. – bfavaretto Mar 24 '13 at 03:10
This answer was very useful for me. Thx a lot! – Forza Dec 10 '13 at 16:01
I had the same problem.. I just added ``return true;`` to the first function and it works a charm. – Colin R. Turner Jan 09 '23 at 19:41

Philip Kirkbride · Accepted Answer · 2016-12-01T13:36:00.697

Looking back at this now, this seems to be how it works with jQuery:

function f1() {
 alert("function one");
}

$.when( f1() ).done(function() {
  alert("function 1 is done running function two");
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

Note: This is identical to my method I posted in the question so essentially it should have worked. Though jQuery may have changed over the last 3 years. Most likely was a problem with functions being called.

score 1 · Answer 3 · answered Sep 30 '13 at 06:52

1

another wild guess:

$.when(saveCanvas(canvas)).done(function(){
    setWallPaper()
});

answered Sep 30 '13 at 06:52

Crash Override

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How to use jQuery .When .done

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