Combine multiple jQuery Deferred objects into a new Deferred object

Question

here's the code: http://jsbin.com/lizami/edit?js,console

Paste the code here as well:

var aaa = $.Deferred();

var bbb = function(data){

    console.log(data);

    var dfd = $.Deferred();
    setTimeout(function(){
        dfd.resolve("bbb is done");
    }, 1000);
    return dfd.promise();
};

var ccc = function(data){
    console.log(data);

    var dfd = $.Deferred();
    setTimeout(function(){
        dfd.resolve("ccc is done");
    }, 1000);
    return dfd.promise();
};

var ddd = function(data){
    console.log(data);

    return data;
};



aaa.then([bbb,ccc]).then(ddd);
aaa.resolve("aaa is done");

What I want is to start two new deferred: bbb and ccc when aaa is resolved. And when both bbb and ccc are resolved. call ddd with the resolved data of bbb and ccc.

Is it possible? The jsbin doesn't work

jfriend00 · Accepted Answer · 2015-10-11 00:04:59Z

3

In jQuery, you can use $.when() to combine multiple promises into one.

aaa.then(function() {
    return $.when(bbb(), ccc());
}).then(ddd);

This will wait for aaa to resolve, then it will run both bbb() and ccc() and when they both resolve, it will then call ddd().

Working demo: http://jsfiddle.net/jfriend00/2f7btsq7/

edited Oct 11, 2015 at 0:04

answered Oct 10, 2015 at 23:56

jfriend00

711k104 gold badges1.1k silver badges1k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

dpr · Accepted Answer · 2020-04-07 20:11:13Z

2

Rather old question but it took me some time to find an answer for a dynamic number of deffereds/promises that are to be combined:

const promises = [];
promises.push($.Deferred());
...
promises.push($.Deferred());
// execute $.when using Function.apply to pass the array of promises as arg
$.when.apply(null, promises).done(function() {
  // executed after all promises are "done"
});

In the context of the OP's question:

aaa.then(function() { return $.when.apply(null, [bbb(), ccc()] }).done(ddd));

edited Apr 7, 2020 at 20:11

answered Apr 7, 2020 at 20:06

dpr

11.1k4 gold badges47 silver badges81 bronze badges

Collectives™ on Stack Overflow

Combine multiple jQuery Deferred objects into a new Deferred object

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related