How to wait for result of two promises, then do something?

Question

Well, subject. Can't figure out...

Condition: both promises start asynchronously and not one after another. Like this:

spashGoing.then(doSomethingForItself());
writingGoing.then(doSomethingForItself2());

DoSomethingAfterBothPromises()

P. S. I use promises from WinJS, not the ES2015/ES2016, but they don't have big defferences.

Answer 1

Thanks @Evan Trimboli with .join! See in comment under topic. I went to this and found more beatiful solution here:

WinJS.Promise.join({ 
     p1: p1, 
     p2: p2, 
     m3: 3})
.then(function (args) {
    //args.p1 = null
    //args.p2 = promise with handle to file
    //args.m3 = 3
    console.log("Joined promise completed");
}, function (error) {
    console.log("Joined promise error '" + error + "' occured but was handled");
}).done();