Node.js

Node.js is a JavaScript runtime environment.

First, Install the Node.js in your computer system.

Windows:

1. first go to the website, https://github.com/coreybutler/nvm-windows
2. download and install nvm for windows

Linux:

1. first go to the website, https://github.com/nvm-sh/nvm
2. curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.1/install.sh | bash or wget -qO- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.1/install.sh | bash
3. Running either of the above commands downloads a script and runs it. The script clones the nvm repository to ~/.nvm, and attempts to add the source lines from the snippet below to the correct profile file (~/.bashrc, ~/.bash_profile, ~/.zshrc, or ~/.profile). If you find the install script is updating the wrong profile file, set the $PROFILE env var to the profile file’s path, and then rerun the installation script.
4. export NVM_DIR="$([ -z "${XDG_CONFIG_HOME-}" ] && printf %s "${HOME}/.nvm" || printf %s "${XDG_CONFIG_HOME}/nvm")" [ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh" # This loads nvm

use nvm to manage the different node version

The default package manager for Node.js is npm.

NPM command

npm -v
npm init -y
npm install
npm uninstall
npm audit fix --force
npm fund
npm prune
npm update

npm init -y

will create a package.json and after install node.js module will generate a package-lock.json

package.json and package-lock.json will used by modules depandency manage.

package-lock.json tracking the exact version of every moduble and dependencies.

Create a Express.js application.

mkdir sample-express
cd sample-express
npm init -y
npm install express@4.18.2

vim index.js
------------------index.js-------------------
const express = require("express");
const server = express();
const port = 3000;

server.get("/", function(req, res) {
    res.send("Hello World!");
});

server.listen(port, function() {
    console.log("Listing on " + port);
});

--------------------------------------------

node index.js
Listing on 3000

NPX

when you installed Node.js, you also installed npx, which stands for node package execute.

npx jsonlint package.json // check valid json format.