CODEWITHSUNDEEP
jqueryarraysdeferred
Kevin Li
Kevin Li

Reputation: 1538

Extracting values from an array of Deferreds

I have an array of Deferred objects, which I'm trying to map to their resolved values once they complete. I want to return the array when everything finishes resolving.

Here's what I have so far:

$.when.apply(null, deferredArray)
.pipe(function(){
  return deferredArray;
});

Unfortunately, this returns the array of Deferred objects in the resolved state. Is there any way I can directly access the resolved elements? I know I can chain .then and .pipe on the resolved array of Deferred objects individually, but this doesn't work well for my purposes.

Upvotes: 2

Views: 688

Answers (2)

Kevin Li
Kevin Li

Reputation: 1538

Here is a hacky solution:

extractDeferredArray = function(array) {
  var deferred, extract, ret;
  ret = [];

  extract = (function() {
    var _i, _len, _results;
    _results = [];
    for (_i = 0, _len = array.length; _i < _len; _i++) {
      deferred = array[_i];
      _results.push(deferred.then(function(value) {
        return ret.push(value);
      }));
    }
    return _results;
  })();

  // Make sure our .then methods have completed
  return $.when.apply(null, extract).pipe(function() {
    return ret;
  });
};

Seems kind of awkward to have to do this.

Upvotes: -1

Felix Kling
Felix Kling

Reputation: 816590

Deferred objects are not designed to return any values. You have to handle the results in callbacks.

The results are passed as arguments to the done, fail or pipe callbacks:

$.when.apply(null, deferredArray).then(function(){
  // arguments[0] is the result of the first deferred object
  // arguments[1] is the result of the second deferred object
  // ...

  // or simple pass it to a function that needs the results:
  someFunction(arguments);
});

Of couse in you can also just set that function as callback:

$.when.apply(null, deferredArray).then(someFunction);

DEMO

Upvotes: 2

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