webpack-bower-externals

Webpack Bower Components externals

Easily exclude Bower components in Webpack (Forked from https://github.com/liady/webpack-node-externals)

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 bower_components dependencies. This library creates an externals function that ignores bower_components when bundling in Webpack.
(Inspired by the great Backend apps with Webpack series)

Quick usage

npm install webpack-bower-externals --save-dev

In your webpack.config.js:

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

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

Detailed overview

Description

This library scans the bower_components folder for all bower_components 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 for the externals to whitelist, so they will be included in the bundle. Can accept exact strings ('module_name'), regex patterns (/^module_name/), or a function that accepts the module name and returns whether it should be included.
Important - if you have set aliases in your webpack config with the exact same names as modules in bower_components, 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 umd for bower components.

options.modulesDir (='bower_components')

The folder in which to search for the bower components.

options.modulesFromFile (=false)

Read the modules from the .bower.json file instead of the bower_components folder.

Example

var bowerExternals = require('webpack-bower-externals');
...
module.exports = {
    ...
    target: 'umd', // important in order not to bundle built-in modules like path, fs, etc.
    externals: [bowerExternals({
        // 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 bower_components folder, so it only leaves unbundled the actual Bower components that are being used.

How can I bundle required assets (i.e css files) from bower_components?

Using the whitelist option, this is possible. We can simply tell Webpack to bundle all files with extensions that are not js/jsx/json, using this [regex](https://regexper.com/#%5C.(%3F!(%3F%3Ajs%7Cjson)%24).%7B1%2C5%7D%24):

...
bowerExternals({
  // load non-javascript files with extensions, presumably via loaders
  whitelist: [/\.(?!(?:jsx?|json)$).{1,5}$/i],
}),
...

Thanks @wmertens for this idea.

Contribute

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

Test

npm run test

License

MIT