Worldly adventures in Node.js

You may recall I was inspired to write software emulating Enigma and the Bombe. Colin suggested I write it in Node.js. Node.js is some sort of JavaScript runtime thing that is event-driven. This is well out of my comfort zone: I have some learning to do.

Hello World

I made a start with that well-known program, Hello World.

In Node.js, it was remarkably easy: I created a file called helloworld.js containing the following code:

console.log('Hello World');

To run this file, I typed:

node helloworld.js

at the command line to obtain this output:

Hello World

Hello World – server edition

There is also a server version. I saved the following code in a file called helloworld_server.js:

const http = require('http');
const hostname = '127.0.0.1';
const port = 3000;
const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello World\n');
});
server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});

At the command line, I ran the program with Node.js and got a successful result:

node helloworld_server.js
Server running at http://127.0.0.1:3000/

This looked promising. I opened my browser and navigated to http://127.0.0.1:3000/; I was shown a page displaying:

Hello World

Another success!

I opened a new command line window while the server was still running, and typed:

curl 127.0.0.1:3000

which output:

Hello World

More success!

(To quit the server, press ctrl+C.)

Now I just need to learn how to do all sorts of other things, and I’ll have my Enigma and Bombe machines built in no time.