Promise [bluebird]

promise.js

var Promise = require('bluebird');
var fs = require('fs');


function readFile(path) {
    var file = new Promise(function(resolve, reject) {
        fs.readFile(path, 'utf8', function(err, data) {
            if(err) {
                reject(err);
            } else {
                resolve(data);
            }
        });
    });
    return file;
}

var path = './package.json';


readFile(path).then(function(data) {
    console.log(data);
}).catch(function(err) {
    console.log(err);
}).done(function(){
    console.log('done');
});