promise-polyfill/src/allSettled.js

function allSettled(arr) {
  var P = this;
  return new P(function(resolve, reject) {
    if (!(arr && typeof arr.length !== 'undefined')) {
      return reject(
        new TypeError(
          typeof arr +
            ' ' +
            arr +
            ' is not iterable(cannot read property Symbol(Symbol.iterator))'
        )
      );
    }
    var args = Array.prototype.slice.call(arr);
    if (args.length === 0) return resolve([]);
    var remaining = args.length;

    function res(i, val) {
      if (val && (typeof val === 'object' || typeof val === 'function')) {
        var then = val.then;
        if (typeof then === 'function') {
          then.call(
            val,
            function(val) {
              res(i, val);
            },
            function(e) {
              args[i] = { status: 'rejected', reason: e };
              if (--remaining === 0) {
                resolve(args);
              }
            }
          );
          return;
        }
      }
      args[i] = { status: 'fulfilled', value: val };
      if (--remaining === 0) {
        resolve(args);
      }
    }

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

export default allSettled;