Running Multiple npm Scripts in Parallel

As a developer, you often need to run multiple scripts simultaneously during development. In this tutorial, we will explore how to run multiple npm scripts in parallel using various methods.

Introduction to npm Scripts

npm (Node Package Manager) allows you to define custom scripts in your package.json file. These scripts can be used to perform a variety of tasks, such as starting a development server, building your application, or running tests.

Running Scripts Sequentially

By default, npm runs scripts sequentially. This means that if you have multiple scripts defined, they will run one after another. However, in many cases, you want to run these scripts simultaneously.

Method 1: Using the & Operator (UNIX-like environments)

In UNIX-like environments, such as Linux or macOS, you can use the & operator to run scripts in parallel. For example:

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

This will run both start-watch and wp-server scripts simultaneously.

Method 2: Using the concurrently Package

The concurrently package allows you to run multiple scripts in parallel. First, install it using:

npm i concurrently --save-dev

Then, define your script as follows:

"scripts": {
  "start-watch": "nodemon run-babel index.js",
  "wp-server": "webpack-dev-server",
  "dev": "concurrently --kill-others \"npm run start-watch\" \"npm run wp-server\""
}

This will run both scripts simultaneously and kill all processes when one of them finishes.

Method 3: Using the npm-run-all Package

The npm-run-all package provides a more flexible way to run multiple scripts in parallel. First, install it using:

npm i npm-run-all --save-dev

Then, define your script as follows:

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

This will run both scripts simultaneously. You can also use the --race option to kill all processes when one of them finishes with a zero exit code.

Conclusion

In this tutorial, we explored three methods for running multiple npm scripts in parallel: using the & operator, the concurrently package, and the npm-run-all package. Each method has its own advantages and disadvantages, and you can choose the one that best fits your needs.