npx is a tool for running npm packages that:

  • live inside of a local node_modules folder or
  • are not installed globally.
# Before
$ node ./node_modules/.bin/mocha

# Now with npx:
$ npx mocha

npx looks into the local /node_modules folder for the package and if it can’t find it, it will download and run it without having that package globally installed.

npx can reach into node_modules to run package binaries

npx is a replacement for installing global packages. It encourages you to install packages locally, but still be able run them as if they were global, just with npx.

$ npm i -D gulp gulp-cli
$ npx gulp

Running gulp locally with npx

Make sure you --save or --save-dev the package first. This keeps dependent packages listed in package.json, so that npx can use the local version instead of downloading it to the npm cache.

npx is a useful tool for easily running npm packages. Just be wary of typos as this method increases the chance of being typosquatted.

npx comes with npm

npx comes bundled with npm version 5.2+ (or as a standalone package). It works by checking if the npm package command exists in your local node_modules/.bin folder, or from a central npx cache and installing any packages needed for that command to run.

Run any one-off package

npx will download and execute any package you give it. This is useful for one-off commands, such as:

Checking the accessibility score of a website.

$ npx pa11y https://scottlogic.com
> Running Pa11y on URL https://scottlogic.com/

npx pa11y

After performing this audit we have promptly looked into the accessibility of our website and how we can improve its Pa11y score.

Creating a boilerplate React app.

$ npx create-react-app harrys-site

Running a static web server.

$ cd my-website
$ npx http-server
> Starting up http-server, serving ./
> Available on:
>  http://192.168.36.65:8080
>  http://127.0.0.1:8080
> Hit CTRL-C to stop the server

Deploying to a live server.

$ cd my-website
$ npx now --public
> Ready! https://test-hffvgcpvvq.now.sh [2s]

npx can also execute a package from a URL, e.g. this GitHub gist:

$ npx https://gist.github.com/zkat/4bc19503fe9e9309e2bfaa2c58074d32
> yay gist

Use it today by updating npm: npm i npm.

$ npx cowsay goodbye!

npx cowsay goodbye!

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