Table of Contents

• Usage
  • Example

Usage#

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

Please see the Command Line Options document for information about different options and ways to run scripts with Node.js.

Example#

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

Commands displayed in this document are shown starting with $ or > to replicate how they would appear in a user's terminal. Do not include the $ and > character they are there to indicate the start of each command.

There are many tutorials and examples that follow this convention: $ or > for commands run as a regular user, and # for commands that should be executed as an administrator.

Lines that don’t start with $ or > character are typically showing the output of the previous command.

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

Now, create an empty project folder called projects, navigate into it: Project folder can be named base on user's current project title but this example will use projects as the project folder.

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.

In Node.js it is considered good style to use hyphens (-) or underscores (_) to separate multiple words in filenames.

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 enter the following command:

$ node hello-world.js

An output like this should appear in the terminal to indicate Node.js server is running:

 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.

Many of the examples in the documentation can be run similarly.