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How to Use `npm link` to Test NPM Packages Locally Before Publishing

· 2 min read
Sahil Phondekar
Sahil Phondekar
Sr. Software Engineer @Everestek

When building your own NPM package (like a React component library), it's essential to test it in a real project before publishing to the registry. This is where npm link comes in handy.

In this post, we’ll walk through how to use npm link to test your local package in another project.

npm link creates a symbolic link between your local NPM package and another project. It allows your test app to use your local package as if it were installed from the registry.

Step-by-Step Guide​

1. Go to Your Package Directory​

cd ~/Projects/my-component-library

Run the following to make it globally available:

npm link

This registers your package globally on your machine.

2. Go to Your Test Project​

Now, open your test project (where you want to use your library):

cd ~/Projects/my-app

Link the package:

npm link my-component-library

This creates a symbolic link from node_modules/my-component-library to your local package source folder.

3. Use the Package in Your App​

Now you can use your package in the test app just like any other dependency:

import { Button } from "my-component-library";

function App() {
  return <Button>Test Button</Button>;
}

Unlinking Later​

When you're done testing, clean up the link:

cd ~/Projects/my-app
npm unlink my-component-library

Then globally remove the link:

cd ~/Projects/my-component-library
npm unlink

Conclusion​

Using npm link is an efficient way to test your NPM packages locally. It mimics the install process while allowing rapid development and testing without publishing to the registry.