promise3.js

var Q = require('q'),
	_ = require('lodash');

var eventualAdd = function(n1, n2) {

	return Q.promise(function(resolve, reject, notify) {

		var n = setInterval(function() {
			notify("working");
		}, 100);

		setTimeout(function() {
			clearInterval(n);
			resolve(n1 + n2);
		}, 500);
	});
};

var res = 0;
var nums = [1,2,3,4,5,6,7,8];
nums = _.chunk(nums, 2);
var promises = [];
for (var i = 0, len = nums.length; i < len; i++) {
	var set = nums[i];
	promises.push(eventualAdd(set[0], set[1]));
}
Q.all(promises)
	.spread(function(a,b,c,d) {
		console.log(a,b,c,d);
	})
	.progress(function(msg) {
		console.log(msg.value);
	})
	.catch(function(err) {
		console.log("ERROR", err);
	});