nodejs
======

(Updated 2024.)

Node or node.js or nodejs is a general purpose programming platform for JavaScript, often used for server-side web development. Node used Google's V8 JavaScript engine and some components written in C; its performance is good.

On Debian:

    # apt-get install nodejs npm

npm is the node package manager.

Node has a REPL, invoked with:

```
$ nodejs
> .help
.break	Sometimes you get stuck, this gets you out
.clear	Alias for .break
.exit	Exit the repl
.help	Show repl options
.load	Load JS from a file into the REPL session
.save	Save all evaluated commands in this REPL session to a file
>
```

A simple nodejs server:

```
const http = require('http');

const server = http.createServer(
	function (req, res) {
		res.writeHead(200, {'Content-Type': 'text/plain'});
		res.end('Hello, World!\n');
	}
)

server.listen(9090, "127.0.0.1");

console.log('Server running at http://127.0.0.1:9090/');
```

Run it like:

    $ node hello.js


# Express

For web apps, many sources recommend using the "express" module to provide basic MVC glue.

    $ npm install express

Express does not include a template engine. Try Jade. http://jade-lang.com/

npm installs node modules at `$NODE_PATH` or `$PWD/node_modules/` by default.

```
var express = require('express');

var app = express.createServer();

app.get('/', function(req, res) {
	res.send('Welcome to node express.');
});

app.listen(9090);
```


# Typescript

TypeScript is a JavaScript variant that adds a static type checker.

```
interface User {
	name: string;
	id: number;
}

const user: User = {
	name: "Paul",
	id: 0
};

function deleteUser(user: User) {
    // ...
}

function getAdminUser(): User {
    // ...
}
```


# Links

* [JavaScript Concepts to Know Before Learning Node.js (freeCodeCamp)](https://www.freecodecamp.org/news/javascript-concepts-to-know-before-learning-node-js/)
* [Express/Node introduction (MDN)](https://developer.mozilla.org/en-US/docs/Learn/Server-side/Express_Nodejs/Introduction)
* [Introduction to Node.js (nodejs.org)](https://nodejs.org/en/learn/getting-started/introduction-to-nodejs)
* [Node.js server without a framework (MDN)](https://developer.mozilla.org/en-US/docs/Learn/Server-side/Node_server_without_framework)
* [TypeScript Tooling in 5 minutes](https://www.typescriptlang.org/docs/handbook/typescript-tooling-in-5-minutes.html)