Node.js

- About this documentation
- Usage and example

- Assertion testing
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# Usage and example#

## Usage#

`node [options] [V8 options] [script.js | -e "script" | - ] [arguments]`

Please see the Command Line Options document for more information.

## Example#

An example of a web server written with Node.js which responds with `'Hello, World!'`:

Commands in this document start with `$` or `>` to replicate how they would appear in a user's terminal. Do not include the `$` and `>` characters. They are there to show the start of each command.

Lines that don’t start with `$` or `>` character show the output of the previous command.

First, make sure to have downloaded and installed Node.js. See this guide for further install information.

Now, create an empty project folder called `projects`, then navigate into it.

Linux and Mac:

    $ mkdir ~/projects
    $ cd ~/projects

Windows CMD:

    > mkdir %USERPROFILE%\projects
    > cd %USERPROFILE%\projects

Windows PowerShell:

    > mkdir $env:USERPROFILE\projects
    > cd $env:USERPROFILE\projects

Next, create a new source file in the `projects` folder and call it `hello-world.js`.

Open `hello-world.js` in any preferred text editor and paste in the following content:

    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}/`);
    });

Save the file, go back to the terminal window, and enter the following command:

    $ node hello-world.js

Output like this should appear in the terminal:

    Server running at http://127.0.0.1:3000/

Now, open any preferred web browser and visit `http://127.0.0.1:3000`.

If the browser displays the string `Hello, World!`, that indicates the server is working.