また新たなクソを生み出してしまったな。

sleepSort.js

"use strict";

function sleepSort(array, callback) {
	array = array || [];
	callback = callback || noop;

	const promises = [], ret = [];
	let retPromise;

	for(let val of array) {
		promises.push(new Promise((resolve) => {
			setTimeout(() => {
				ret.push(val);
				resolve();
			}, val * 1000);
		}));
	}

	retPromise = Promise.all(promises)
		.then(() => {
			return ret;
		});

	retPromise.then(callback);

	return retPromise;
}

function noop() {}

Array.prototype.sleepSort = function(callback) {
	return sleepSort(this, callback);
};

例によって Babel ってどうぞ。

[1, 1, 4, 5, 1, 4].sleepSort().then((val) => {
  console.log(val);
});