Object Key Sum

objectKeySum.js

var _n = require('underscore');
var async = require('async');

//sum all the keys in array of objects 
function objectKeySum(object, properties) {
	var response = {};
	async.forEachOf(
		properties,
		function(value, key, callback) {
			var summed = _n.reduce(_n.pluck(object,value), function (t,h) { return t+h }, 0);
			response[value] = summed;
			callback(response);
		});
		return response;
}