Display PDF by using node express

app.js

/*
$ npm init
$ npm install express
$ touch app.js
$ node app.js
*/

var express = require("express"),
  fs = require("fs"),
  app = express();

app.get("/", function(req, res) {
  fs.readFile("helloworld.pdf", function(err, data) {
    res.contentType("application/pdf");
    res.send(data);
  });
});
app.listen(3000, function() {
  console.log("Listening port: 3000!");
});