Node.js NPM
What is NPM?
NPM is a package manager for Node.js packages, or modules if you like.
www.npmjs.com hosts thousands of free packages to download and use.
The NPM program is installed on your computer when you install Node.js
If you installed Node.js, NPM is already ready to run on your computer!
What is a Package?
A package in Node.js contains all the files you need for a module.
Modules are JavaScript libraries you can include in your project.
Download a Package
Downloading a package is very easy.
Open the command line interface and tell NPM to download the package you want.
I want to download a package called "upper-case":
Download "upper-case":
C:\Users\Your Name>npm install upper-case
Now you have downloaded and installed your first package!
NPM creates a folder named "node_modules", where the package will be placed.
All packages you install in the future will be placed in this folder.
My project now has a folder structure like this:
C:\Users\My Name\node_modules\upper-case
Using a Package
Once the package is installed, it is ready to use.
Include the "upper-case" package the same way you include any other module:
let uc = require('upper-case');
Create a Node.js file that will convert the output "Hello World!" into upper-case letters:
Example
let http = require('http');
let uc = require('upper-case');
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/html'});
res.write(uc.upperCase("Hello World!"));
res.end();
}).listen(8080);
Run example »
Save the code above in a file called "demo_uppercase.js", and initiate the file:
Initiate demo_uppercase:
C:\Users\Your Name>node demo_uppercase.js
If you have followed the same steps on your computer, you will see the same result as the example: http://localhost:8080
Global Packages
Packages can be installed globally, making them available as command-line tools anywhere on your system.
Global packages are typically used for CLI tools and utilities.
Install a package globally:
npm install -g package-name
Example: Install the http-server package globally
npm install -g http-server
After installation, you can run the package from any directory:
http-server
Note: On some systems, you might need administrator/root privileges to install packages globally.
On Unix-like systems, use sudo before the command.
Updating Packages
To keep your packages up to date, you can update them using the following commands:
Update a specific package:
npm update package-name
Update all packages in your project:
npm update
Check for outdated packages:
npm outdated
Tip: To update npm itself, run: npm install -g npm@latest
Uninstalling a Package
To remove a package that you no longer need, you can use the uninstall command:
Remove a package:
npm uninstall package-name
Remove a global package:
npm uninstall -g package-name
Remove a package and its dependencies:
npm uninstall --save package-name
Note: The --save flag updates your package.json file to remove the dependency.
For older versions of npm, you might need to use --save-dev for development dependencies.
