How to add a custom script to package.json that runs a javascript file?

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06-09-2024

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Running Custom Scripts with npm: A Guide to package.json

Have you ever wanted to streamline your development workflow by running specific scripts within your project? This is where package.json's scripts property comes in handy. This article will guide you through adding custom scripts to your package.json file and executing them using npm, all while ensuring they function correctly in any environment.

Understanding the Problem

Let's address the issue raised by a Stack Overflow user [referencing the original Stack Overflow post here]: They want to run a JavaScript file (script1.js) using a custom command (script1) within their project directory. However, running script1 directly results in the error "zsh: command not found: script1."

The Solution: package.json and npm Scripts

The package.json file, found at the root of your project, acts as a central hub for project metadata. Within it lies the scripts property, allowing you to define custom commands that are executed using npm (Node Package Manager).

Adding a Script to package.json

To solve the user's problem, we'll modify their package.json file by adding a script named "script1" that will run node script1.js:

{
  "scripts": {
    "script1": "node script1.js"
  }
}

Running Your Script

Now, open your terminal within the project directory and execute the following command:

npm run script1

This will trigger the execution of your defined script, running node script1.js and achieving the desired result.

Key Points to Remember

• Relative Paths: The path provided within the script definition should be relative to the root directory of your project. If script1.js is located in a subdirectory, adjust the path accordingly. For example, scripts/script1.js.
• Multiple Scripts: You can define multiple scripts within the scripts object, each performing a different action. This allows for organization and easy execution of complex workflows.
• Environment Variables: npm provides access to environment variables within scripts. You can use $npm_package_name to reference the package name or $npm_package_version for the version number.
• Npm Documentation: For a comprehensive understanding of package.json and its scripts property, consult the official npm documentation: https://docs.npmjs.com/cli/v8/configuring-npm/package-json

Additional Tips and Examples:

• Running Tests: "npm run test" is a widely used convention to execute tests within a project. You can add a script like "test": "jest" to run tests with the Jest framework.
• Building for Production: "npm run build" is commonly used to build a production-ready version of your project. You can add a script like "build": "webpack --mode production" to utilize Webpack for bundling.
• Deploying to a Server: "npm run deploy" can be defined to deploy your project to a remote server using tools like FTP or Git.

Conclusion:

By utilizing the scripts property in your package.json file, you can easily define and run custom scripts within your project, improving efficiency and streamlining your development workflow. Remember, the scripts property is a powerful tool for automating tasks, making your development process more organized and less prone to errors.