You can decide what files people get when they download your package in three ways:

1. With the .gitignore file
2. With the .npmignore file
3. With the files property

We'll look at each method and discuss which methods you should (or shouldn't) be using.

Excluding files with gitignore

First, npm will check your repository for a .gitignore file. If there is a .gitignore file, npm will ignore files according to what's listed in the .gitignore file.

This is the most common way package authors prevent people from downloading extra files.

Let's go through a simple example. Say you have the following directory structure.

- project-name/
  |- index.js 
  |- package.json
  |- node_modules/

Let's say you don't want people to download the node_modules folder. You also don't want to save the node_modules in the Git repository.

What you'll do is create a .gitignore file.

# .gitignore 
node_modules 

In this case, both Git and npm ignore the node_modules folder.

Blacklisting files with npmignore

A second way is to blacklist files with a .npmignore file. The .npmignore file works the same way as a .gitignore file. If a file is listed in the .npmignore file, the file will be excluded from the package.

Important note: If you have a .npmignore file, npm will use the .npmignore file. npm will ignore the .gitignore file altogether. (Many developers mistakenly believe npm will use both .npmignore and .gitignore files. Don't make the same mistake!).

You can use this method if you want to exclude files from the package, but keep them in the Git repository.

Let's walk through another example. Let's say you've written tests for your package and you put them all in a tests folder. This is your directory structure:

- project-name/
  |- index.js 
  |- package.json
  |- node_modules/
  |- tests/

You want to exclude node_modules from both your Git repository and your package.

You want to include tests in your Git repository, but exclude it from the package.

If you opt for the npmignore file method, you can write these in your .gitignore and .npmignore files:

# .gitignore 
node_modules

# .npmignore
node_modules
tests

Whitelisting files with the files property

A third method is to whitelist files you want to be included in the package.json file, under the files property.

Note: npm will prioritize this method over other methods mentioned above. This is the easiest method to limit what files others download.

This approach is pretty simple. What you need is to create a files property in the package.json file. Then, provide a list of files you'd like to include.

Here's an example:

{
  "files": [
    "index.js"
  ]
}

Note: Some files, like package.json, is always included in a package. You don't have to write these files in the files property.

Which method to use?

All three methods work. Pick the one you're most comfortable with. For simple projects, the .gitignore file method should suffice.

If your project is more advanced, you might want to blacklist files with .npmignore or whitelist files with the files property. Pick one. There's no need for both.

A quick tip

You can use npm pack to generate a package. This package includes files other people will get.

npm pack

Try it!

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