Creating Node.js modules

Node.js modules are a type of package that can be published to npm.

Overview

  1. Create a package.json file
  2. Create the file that will be loaded when your module is required by another application
  3. Test your module

Create a package.json file

  1. To create a package.json file, on the command line, in the root directory of your Node.js module, run npm init:
  2. Provide responses for the required fields (name and version), as well as the main field:
    • name: The name of your module.
    • version: The initial module version. We recommend following semantic versioning guidelines and starting with 1.0.0.
    • main: The name of the file that will be loaded when your module is required by another application. The default name is index.js.

For more information on package.json files, see “Creating a package.json file”.

Create the file that will be loaded when your module is required by another application

Once your package.json file is created, create the file that will be loaded when your module is required. The default name for this file is index.js.

In the file, add a function as a property of the exports object. This will make the function available to other code:

exports.printMsg = function() {
  console.log("This is a message from the demo package");
}

Test your module

  1. Publish your package to npm:
  2. On the command line, create a new test directory outside of your project directory.
    mkdir test-directory
    
  3. Switch to the new directory:
    cd /path/to/test-directory
    
  4. In the test directory, install your module:
    npm install <your-module-name>
    
  5. In the test directory, create a test.js file which requires your module and calls your module as a method.
  6. On the command line, run node test.js. The message sent to the console.log should appear.

Resources


< Creating a package.json file | About package README files >