How to run multiple npm scripts in parallel

Question

In my package.json I have these two scripts:

  "scripts": {
    "start-watch": "nodemon run-babel index.js",
    "wp-server": "webpack-dev-server",
  }

I have to run these 2 scripts in parallel everytime I start developing in Node.js. The first thing I thought of was adding a third script like this:

"dev": "npm run start-watch && npm run wp-server"

but that will wait for start-watch to finish before running wp-server.

How can I run these in parallel?

Answer 1

You should use npm-run-all (or concurrently, parallelshell), because it has more control over starting and killing commands. The operators &, | are bad ideas because you'll need to manually stop it after all tests are finished.

This is an example for protractor testing through npm:

scripts: {
  "webdriver-start": "./node_modules/protractor/bin/webdriver-manager update && ./node_modules/protractor/bin/webdriver-manager start",
  "protractor": "./node_modules/protractor/bin/protractor ./tests/protractor.conf.js",
  "http-server": "./node_modules/http-server/bin/http-server -a localhost -p 8000",
  "test": "npm-run-all -p -r webdriver-start http-server protractor"
}

-p = Run commands in parallel.

-r = Kill all commands when one of them finishes with an exit code of zero.

Running npm run test will start Selenium driver, start http server (to serve you files) and run protractor tests.