Easy way to retrieve async callback info in a async.each

Question

There is a point I often face in my node js work and I would like to know the best way to handle it.

I have an asynchronous call to an API that callbacks with a data info, for example a traffic time.

I need to iterate over a collection of data for which i need to get the traffic time. I use async.each to do this.

How can I collect all the traffic times once the requests are all done ?

For now, the solution I am currently working with is passing an additional array argument to the asynchronous call that is an array in which I push the data result and I then callback the array.

I can get all the infos I need in this array once everything is done but, since it is a move I need to do in a lot of different contexts, I would like to know if there is a simpliest way to treat this.

Thank you very much :)

Answer 1

async.map() works like async.each() , and allows you to pass a result to the callback. The final callback is then called with an array containing the results.

See https://github.com/caolan/async#map

eg (untested, and could be shorter, but I wrote some stuff explicitly for the example)

async.map(dataCollection, function(data, done) {
    trafficTime.get(data, function(err, time) {
        if (err) return done(err);
        done(null, time);
    });
}, function(err, times) {
    # times is the results array
});