Promises Basics in JavaScript

basic_promise_err_handle.js

// add some basic error handling
var q = require("q");
var fs = require("fs");
function qread(file) {
	var _q = q.defer();
	fs.readFile(file, "utf-8", function (err, data) {
		if (err) { _q.reject(new Error(err)) 
		} else { _q.resolve(data); }
	});
	return _q.promise;
}

basic_promise_example.js

var q = require("q");
var fs = require("fs");

// wrap fs.read in a promise
function qread(file) {
	var _q = q.defer();
	fs.readFile(file, "utf-8", function (err, data) { _q.resolve(data) });
	return _q.promise;
}