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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!
A package in Node.js contains all the files you need for a module. Modules are JavaScript libraries you can include in your project.
Downloading a package is very easy. Open the command line interface and tell NPM to download the package you want.
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I want to download a package called "upper - case":
Download "upper - case":C:\Users\
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> npm install upper - caseNow 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\
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\node_modules\upper - caseOnce the package is installed, it is ready to use.
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Include the "upper - case" package the same way you include any other module:let uc = require('upper-case');Formula
Create a Node.js file that will convert the output "Hello World!" into upper - case letters: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);
Save the code above in a file called "demo_uppercase.js", and initiate the file:Initiate demo_uppercase: C:\Users\
>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
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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.
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npm install - g package - nameExample: Install the http-server package globally npm install -g http-server After installation, you can run the package from any directory:
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http - serverFormula
On some systems, you might need administrator/root privileges to install packages globally.
On Unix - like systems, use sudo before the command.To keep your packages up to date, you can update them using the following commands:
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npm update package - nameUpdate all packages in your project: npm update
npm outdated
To update npm itself, run:
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npm install - g npm@latestTo remove a package that you no longer need, you can use the uninstall command:
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npm uninstall package - nameFormula
npm uninstall - g package - nameRemove a package and its dependencies:
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npm uninstall -- save package - name--save flag updates your package.json file to remove the dependency. For older versions of npm, you might need to use
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-- save - dev for development dependencies.