Introduction to Concurrently

Concurrently is a powerful Node.js utility that allows developers to manage multiple processes simultaneously. It’s especially useful in cases where you need to run multiple commands or scripts at the same time during development.

Installing Concurrently

  
  npm install concurrently --save-dev
  

Basic Usage

You can run multiple commands concurrently using the following syntax:

  
  concurrently "command1" "command2"
  

Advanced Usage

Here are some examples to help you leverage the full power of Concurrently:

Kill Other Commands if One Fails

  
  concurrently --kill-others "command1" "command2"
  

Restart Commands

  
  concurrently --restart-tries 3 "command1" "command2"
  

Raw Mode

To disable clearing of the screen between command outputs:

  
  concurrently --raw "command1" "command2"
  

Logging Date

You can include a timestamp for each log entry:

  
  concurrently --timestamp "command1" "command2"
  

Example Application

Let’s consider an example of setting up a Node.js application where you run the backend and frontend servers concurrently:

Project Structure

  
  my-project/
  |-- package.json
  |-- backend/
  |   |-- server.js
  |-- frontend/
  |   |-- package.json
  |   |-- public/
  

Install Dependencies

  
  cd backend
  npm install
  cd ../frontend
  npm install
  

Configure Concurrently

Add the following scripts to your root package.json file:

  
  {
    "scripts": {
      "serve-backend": "node backend/server.js",
      "serve-frontend": "npm start --prefix frontend",
      "start": "concurrently \"npm run serve-backend\" \"npm run serve-frontend\""
    }
  }
  

Now, you can run both servers concurrently with:

  
  npm start
  

This will launch both your backend server and frontend server in parallel, speeding up your development workflow.

For further customization, you can refer to concurrently documentation.

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