Difference between npx and npm?

npm - Package manager for JavaScript, just like: pip (Python), Maven (Java), NuGet (.NET), Composer (PHP), RubyGems (Ruby), ...

npx - runs a command of a package without installing it explicitly.

Use cases:

  • You don't want to install packages neither globally nor locally.
  • You don't have permission to install it globally.
  • Just want to test some commands.
  • Sometime, you want to have a script command (generate, convert something, ...) in package.json to execute something without installing these packages as project's dependencies.

Syntax:

npx [options] [-p|--package <package>] <command> [command-arg]...

Package is optional:

npx   -p uglify-js         uglifyjs --output app.min.js app.js common.js
      +----------------+   +--------------------------------------------+
      package (optional)   command, followed by arguments

For example:

Start a HTTP Server      : npx http-server
Lint code                : npx eslint ./src
                         # Run uglifyjs command in the package uglify-js
Minify JS                : npx -p uglify-js uglifyjs -o app.min.js app.js common.js
Minify CSS               : npx clean-css-cli -o style.min.css css/bootstrap.css style.css
Minify HTML              : npx html-minifier index-2.html -o index.html --remove-comments --collapse-whitespace
Scan for open ports      : npx evilscan 192.168.1.10 --port=10-9999
Cast video to Chromecast : npx castnow http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ForBiggerFun.mp4

More about command:

  • https://docs.npmjs.com/files/package.json#bin
  • https://github.com/mishoo/UglifyJS2/blob/master/package.json#L17

npx is a npm package runner (x probably stands for eXecute). One common way to use npx is to download and run a package temporarily or for trials.

create-react-app is an npm package that is expected to be run only once in a project's lifecycle. Hence, it is preferred to use npx to install and run it in a single step.

As mentioned in the main page https://www.npmjs.com/package/npx, npx can run commands in the PATH or from node_modules/.bin by default.

Note: With some digging, we can find that create-react-app points to a Javascript file (possibly to /usr/lib/node_modules/create-react-app/index.js on Linux systems) that is executed within the node environment. This is simply a global tool that does some checks. The actual setup is done by react-scripts, whose latest version is installed in the project. Refer https://github.com/facebook/create-react-app for more info.


NPM is a package manager, you can install node.js packages using NPM

NPX is a tool to execute node.js packages.

It doesn't matter whether you installed that package globally or locally. NPX will temporarily install it and run it. NPM also can run packages if you configure a package.json file and include it in the script section.

So remember this, if you want to check/run a node package quickly without installing locally or globally use NPX.

npM - Manager

npX - Execute - easy to remember


Introducing npx: an npm package runner

NPM - Manages packages but doesn't make life easy executing any.
NPX - A tool for executing Node packages.

NPX comes bundled with NPM version 5.2+

NPM by itself does not simply run any package. It doesn't run any package as a matter of fact. If you want to run a package using NPM, you must specify that package in your package.json file.

When executables are installed via NPM packages, NPM links to them:

  1. local installs have "links" created at ./node_modules/.bin/ directory.
  2. global installs have "links" created from the global bin/ directory (e.g. /usr/local/bin) on Linux or at %AppData%/npm on Windows.

Documentation you should read

NPM:

One might install a package locally on a certain project:

npm install some-package

Now let's say you want NodeJS to execute that package from the command line:

$ some-package

The above will fail. Only globally installed packages can be executed by typing their name only.

To fix this, and have it run, you must type the local path:

$ ./node_modules/.bin/some-package

You can technically run a locally installed package by editing your packages.json file and adding that package in the scripts section:

{
  "name": "whatever",
  "version": "1.0.0",
  "scripts": {
    "some-package": "some-package"
  }
}

Then run the script using npm run-script (or npm run):

npm run some-package

NPX:

npx will check whether <command> exists in $PATH, or in the local project binaries, and execute it. So, for the above example, if you wish to execute the locally-installed package some-package all you need to do is type:

npx some-package

Another major advantage of npx is the ability to execute a package which wasn't previously installed:

$ npx create-react-app my-app

The above example will generate a react app boilerplate within the path the command had run in, and ensures that you always use the latest version of a generator or build tool without having to upgrade each time you’re about to use it.

Use-Case Example:

npx command may be helpful in the script section of a package.json file, when it is unwanted to define a dependency which might not be commonly used or any other reason:

"scripts": {
    "start": "npx [email protected]",
    "serve": "npx http-server"
}

Call with: npm run serve

Related questions:

  1. How to use package installed locally in node_modules?
  2. NPM: how to source ./node_modules/.bin folder?
  3. How do you run a js file using npm scripts?

Tags:

Javascript

Npm

Npx

Recent Posts