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:
   • For scoped modules, run npm init --scope=@scope-name
   • For unscoped modules, 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.

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

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:

   • For private packages and unscoped packages, use npm publish.
   • For scoped public packages, use npm publish --access public

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.

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