How to run multiple scripts in parallto using Yarn

When managing projects with Yarn, we often need to run multiple scripts in parallel to improve efficiency, especially when handling independent tasks. Yarn itself does not natively support running multiple scripts in parallel, but we can achieve this using various tools and methods.

Using yarn-run-all or npm-run-all Tools

A common approach is to use yarn-run-all (or npm-run-all, which are generic CLI tools) to manage the parallel or sequential execution of npm/yarn scripts. This is particularly useful for running multiple services or tasks simultaneously during development.

Installation Method:

bash
yarn add npm-run-all --dev

Usage Example: Assume you have two scripts to run in parallel: one to start the frontend development server and another to start an API mock server. Configure them in package.json as follows:

json
{
  "scripts": {
    "start:dev": "react-scripts start",
    "start:api": "json-server --watch db.json",
    "start": "run-p start:dev start:api"
  }
}

Here, run-p is the command from npm-run-all for parallel execution. Running yarn start will launch both the development server and the API server.

Using Parallel Shell Commands

For simple scripts on Unix-like systems (such as Linux or macOS), you can leverage shell features to run tasks in parallel.

Example:

json
{
  "scripts": {
    "start:dev": "react-scripts start",
    "start:api": "json-server --watch db.json",
    "start": "yarn start:dev & yarn start:api"
  }
}

The & symbol allows the shell to run commands in the background, enabling simultaneous execution of multiple commands.

Using Other Tools

Tools like concurrently can also run multiple commands in parallel.

Installation Method:

bash
yarn add concurrently --dev

Usage Example:

json
{
  "scripts": {
    "start:dev": "react-scripts start",
    "start:api": "json-server --watch db.json",
    "start": "concurrently "yarn start:dev" "yarn start:api""
  }
}

With concurrently, output management in the command line is more straightforward due to its support for log colors and prefixes, making it easier to track multiple parallel tasks.

In summary, by leveraging these tools and methods, we can effectively utilize Yarn to run multiple scripts in parallel, thereby enhancing the efficiency of development and deployment processes.