Most Common NPM Commands

What is NPM?

NPM stands for Node Package Manager. It comes with Node.js, a tool that runs JavaScript outside the browser. A package is a ready-made piece of code that someone else wrote. NPM downloads and manages these packages for you, like an app store for code.

Check that NPM is installed

node -v
npm -v

These print the version numbers of Node.js and NPM. If you see an error, install Node.js first.

Start a project

npm init

This asks a few questions and creates a package.json file. That file is the list of your project's details and packages. Use npm init -y to accept all defaults.

Install packages

npm install express

This downloads the package named express into a node_modules folder and adds it to package.json.

npm install

Without a name, this installs every package listed in package.json. Use it after you download someone's project.

npm install --save-dev nodemon

This installs a package that you only need while building, not on the live site.

npm install -g pm2

The -g flag installs the package globally. That means it works from anywhere on the computer. You may need admin rights.

Remove and update

npm uninstall express

This removes a package from your project.

npm update

This updates packages to newer versions allowed by package.json. Take a backup first, because updates can break code.

npm outdated

This lists packages that have newer versions.

See what is installed

npm list

This shows installed packages. Add --depth=0 to show only the top level.

Run your scripts

npm start
npm test
npm run build

These run the scripts defined in the scripts part of package.json. npm run name works for any script name.

Fix security problems

npm audit
npm audit fix

The first checks your packages for known security problems. The second tries to fix them.

Clean up

npm cache clean --force

This clears NPM's download cache. Use it when installs act strangely.

Quick recap

• npm init starts a project.
• npm install name adds a package; npm install adds all.
• npm uninstall removes; npm update updates.
• npm start and npm run run scripts.
• npm audit checks for security problems.