index.js

var express = require('express');
var routes = require('./routes/routes');
var bodyParser = require('body-parser');

var app = express();

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));

app.use(function (req, res, next) {
    // Website you wish to allow to connect
    res.setHeader('Access-Control-Allow-Origin', '*');
    // Request methods you wish to allow
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');
    // Request headers you wish to allow
    res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With, Content-Type');
    // Set to true if you need the website to include cookies in the requests sent
    // to the API (e.g. in case you use sessions)
    res.setHeader('Access-Control-Allow-Credentials', true);
    // Pass to next layer of middleware
    next();
});

routes(app);

app.listen(3000)