npm run-script <command> [-- <args>...] alias: npm run
This runs an arbitrary command from a package's "scripts" object. If no "command" is provided, it will list the available scripts. run[-script] is used by the test, start, restart, and stop commands, but can be called directly, as well. When the scripts in the package are printed out, they're separated into lifecycle (test, start, restart) and directly-run scripts.
As of npm@2.0.0 http://blog.npmjs.org/post/98131109725/npm-2-0-0, you can use custom arguments when executing scripts. The special option -- is used by getopt http://goo.gl/KxMmtG to delimit the end of the options. npm will pass all the arguments after the -- directly to your script:
npm run test -- --grep="pattern"
The arguments will only be passed to the script specified after npm run and not to any pre or post script.
The env script is a special built-in command that can be used to list environment variables that will be available to the script at runtime. If an "env" command is defined in your package it will take precedence over the built-in.
In addition to the shell's pre-existing PATH, npm run adds node_modules/.bin to the PATH provided to scripts. Any binaries provided by locally-installed dependencies can be used without the node_modules/.bin prefix. For example, if there is a devDependency on tap in your package, you should write:
"scripts": {"test": "tap test/\*.js"}
instead of "scripts": {"test": "node_modules/.bin/tap test/\*.js"} to run your tests.
npm run sets the NODE environment variable to the node executable with which npm is executed. Also, the directory within which it resides is added to the PATH, if the node executable is not in the PATH.
If you try to run a script without having a node_modules directory and it fails, you will be given a warning to run npm install, just in case you've forgotten.