Promises

promise.js

# Then
var Promise = require('promise');
var fs = require('fs')
var read = Promise.denodeify(fs.readFile)

#Bluebird #1
var Promise = require('bluebird');
var fs = require('fs');
var readFile = Promise.promisify(fs.readFile);

#Bluebird #2
var Promise = require('bluebird');
var fs = require('fs');
Promise.promisifyAll(fs);
var readFile = fs.readFileAsync

readFile("myfile.js", "utf8").then(function(contents) {
    return eval(contents);
}).then(function(result) {
    console.log("The result of evaluating myfile.js", result);
}).catch(SyntaxError, function(e) {
    console.log("File had syntax error", e);
//Catch any other error
}).catch(function(e) {
    console.log("Error reading file", e);
});