How to Create Node.js Modules

Node.js modules are a type of package that can be published to npm. To create a new module, start by creating a package.json file.

Use npm init to create package.json. It will prompt you for values for fields. The two required fields are 'name' and 'version'. You'll also need to set a value for 'main'. You can use the default, index.js. These steps are described in detail in Chapter 5.

If you want to add information for the author field, use the following format (email and website are both optional):

Your Name <[email protected]> (http://example.com)

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

In that 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:

1. Publish your package to npm.
2. Make a new directory outside of your project.
3. Switch to the new directory (cd)
4. Run npm install <package>.
5. Create a test.js file which requires the package and calls the method.
6. Run node test.js. The message sent to the console.log should appear.

Learn More

To understand types of packages, click here.