Passing arguments to npm script in package.json

Question

Is there a way to pass arguments inside of the package.json command?

My script:

"scripts": {
  "test": "node mytest.js $1 $2 | node_modules/tap-difflet/bin/tap-difflet"
}

cli npm run test 8080 production

Then on mytest.js I'd like to get the arguments with process.argv

Answer 1

Passing arguments to script

To pass arguments to npm script, you should provide them after -- for safety.

In your case, -- can be omitted. They behaves the same:

npm run test -- 8080 production
npm run test 8080 production

But when the arguments contain option(s) (e.g. -p), -- is necessary otherwise npm will parse them and treat them as npm's option.

npm run test -- 8080 -p

Use positional parameters

The arguments are just appended to the script to be run. Your $1 $2 won't be resolved. The command that npm actually runs is:

node mytest.js $1 $2 | node_modules/tap-difflet/bin/tap-difflet "8080" "production"

In order to make position variable works in npm script, wrap the command inside a shell function:

"scripts": {
  "test": "run(){ node mytest.js $1 $2 | node_modules/tap-difflet/bin/tap-difflet; }; run"
}

Or use the tool scripty and put your script in an individual file.

package.json:

"scripts": {
  "test": "scripty"
}

scripts/test:

#!/usr/bin/env sh
node mytest.js $1 $2 | node_modules/tap-difflet/bin/tap-difflet