tutorial.md

Node Modules “Hello World” Tutorial

This tutorial is meant to show what the user experience would be like for a user running Node’s classic “Hello World” server example in a version of Node that implements the File Specifier Resolution proposal. The example has been adapted to use import syntax instead of require.

Tutorial

Let’s get started with Node.js! In this tutorial, we’re going to create a web server that listens at http://localhost:3000 and responds to every request with the message Hello World. The tutorial assumes you already have the latest Node.js installed, which includes the latest version of NPM.

First, create a new folder hello-world-server and navigate into it in a command prompt window.

Run this command:

npm init

NPM will ask you a series of questions. You can simply press enter to accept the defaults, or answer each question per your preference:

This utility will walk you through creating a package.json file.
It only covers the most common items, and tries to guess sensible defaults.

See `npm help json` for definitive documentation on these fields
and exactly what they do.

Use `npm install <pkg>` afterwards to install a package and
save it as a dependency in the package.json file.

Press ^C at any time to quit.
package name: (hello-world-server)
version: (1.0.0)
description: A web server that says hello!
use import/export syntax: (yes)
entry point: (index.js)
test command:
git repository:
keywords:
author:
license: (ISC)
About to write to /tmp/hello-world-server/package.json:

{
  "name": "hello-world-server",
  "version": "1.0.0",
  "description": "A web server that says hello!",
  "type": "esm",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC"
}


Is this OK? (yes)

You should now have a package.json in your hello-world-server folder, with the contents as above. This describes the files in this folder (the “package”) both for Node and for other packages to know how to interpret them.

Now create an index.js file in the folder, with the following contents:

import http from '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}/`);
});

This code creates a web server listening on localhost port 3000, responding to every request with the text Hello World. Let’s see it in action!

node index.js

And in a web browser, go to http://localhost:3000. You should see the text Hello World!

Try It Today

You can try this tutorial yourself by using a fork of Node that implements the modules proposals:

git clone git clone git@github.com:guybedford/node node-guybedford
cd node-guybedford
git checkout irp-implementation
# Build per https://github.com/nodejs/node/blob/master/doc/guides/building-node-with-ninja.md
# Install Ninja if needed (Mac): brew install ninja
./configure --ninja
ninja -C out/Release
ln -fs out/Release/node node

Note that this branch doesn’t have an updated NPM, so you need to replace the contents of your generated package.json with the contents shown in the tutorial above. Once you’ve done that, assuming you’ve completed the tutorial and saved to ~/Sites/hello-world-server:

./node ~/Sites/hello-world-server/index.js