Wait until all promises complete even if some rejected

Question

Let\'s say I have a set of Promises that are making network requests, of which one will fail:

// http://does-not-exist will throw a TypeError
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Answer 1

var err;
Promise.all([
    promiseOne().catch(function(error) { err = error;}),
    promiseTwo().catch(function(error) { err = error;})
]).then(function() {
    if (err) {
        throw err;
    }
});

The Promise.all will swallow any rejected promise and store the error in a variable, so it will return when all of the promises have resolved. Then you can re-throw the error out, or do whatever. In this way, I guess you would get out the last rejection instead of the first one.