Webpack node modules externals

Easily exclude node modules in Webpack

Webpack allows you to define externals - modules that should not be bundled.

When bundling with Webpack for the backend - you usually don't want to bundle its node_modules dependencies. This library creates an externals function that ignores node_modules when bundling in Webpack.
(Inspired by the great Backend apps with Webpack series)

Quick usage

npm install webpack-node-externals --save-dev

In your webpack.config.js:

var nodeExternals = require('webpack-node-externals');
...
module.exports = {
    ...
    target: 'node', // in order to ignore built-in modules like path, fs, etc.
    externals: [nodeExternals()], // in order to ignore all modules in node_modules folder
    ...
};

And that's it. All node modules will no longer be bundled but will be left as require('module').

Detailed overview

Description

This library scans the node_modules folder for all node_modules names, and builds an externals function that tells Webpack not to bundle those modules, or any sub-modules of theirs.

Configuration

This library accepts an options object.

options.whitelist (=[])

An array of paths for the externals to whitelist, so they will be included in the bundle. Can accept exact strings ('module_name') or regex patterns (/^module_name/).
Important - if you have set aliases in your webpack config with the exact same names as modules in node_modules, you need to whitelist them so Webpack will know they should be bundled.

options.importType (='commonjs')

The method in which unbundled modules will be required in the code. Best to leave as commonjs for node modules.

options.modulesDir (='node_modules')

The folder in which to search for the node modules.

options.modulesFromFile (=false)

Read the modules from the package.json file instead of the node_modules folder.

Example

var nodeExternals = require('webpack-node-externals');
...
module.exports = {
    ...
    target: 'node', // important in order not to bundle built-in modules like path, fs, etc.
    externals: [nodeExternals({
        // this WILL include `jquery` and `webpack/hot/dev-server` in the bundle, as well as `lodash/*`
        whitelist: ['jquery', 'webpack/hot/dev-server', /^lodash/]
    })],
    ...
};

For most use cases, the defaults of importType and modulesDir should be used.

Q&A

Why not just use a regex in the Webpack config?

Webpack allows inserting regex in the externals array, to capture non-relative modules:

{
    externals: [
        // Every non-relative module is external
        // abc -> require("abc")
        /^[a-z\-0-9]+$/
    ]
}

However, this will leave unbundled all non-relative requires, so it does not account for aliases that may be defined in webpack itself. This library scans the node_modules folder, so it only leaves unbundled the actual node modules that are being used.

Contribute

Contributions and pull requests are welcome. Please run the tests to make sure nothing breaks.

Test

npm run test

License

MIT