CODEWITHSUNDEEP
javascriptajax
etoxin
etoxin

Reputation: 5274

How would I wait for a series of async tasks to complete in js?

I need to perform a GET request to an API multiple times in a function. I then need to handle all the responses as a whole once they have all yielded responses. What is the best JS design to do this?

edit: I originally asked for a Promise.all() polyfill. But I feel like I don't need all the functionality of promises and looking for a simpler solution.

I basically need Promise.all(iterable); functionailty in native JS.

Upvotes: 1

Views: 44

Answers (1)

Charlie
Charlie

Reputation: 23798

This is a polyfill for Promise.all

 Promise.all = function (arr) {
    var args = Array.prototype.slice.call(arr);

    return new Promise(function (resolve, reject) {
      if (args.length === 0) return resolve([]);
      var remaining = args.length;

      function res(i, val) {
        try {
          if (val && (typeof val === 'object' || typeof val === 'function')) {
            var then = val.then;
            if (typeof then === 'function') {
              then.call(val, function (val) {
                res(i, val);
              }, reject);
              return;
            }
          }
          args[i] = val;
          if (--remaining === 0) {
            resolve(args);
          }
        } catch (ex) {
          reject(ex);
        }
      }

      for (var i = 0; i < args.length; i++) {
        res(i, args[i]);
      }
    });
  };

This code is a part of this library.

Upvotes: 3

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