extract-modules-webpack-plugin

Extract Modules Webpack Plugin

Please note that this plugin is experimental for now. I only test it on my projects which all have a manifest declared in the CommonsChunkPlugin. Not sure how it will behave without it. It's also derived from the original plugin split-by-name-webpack-plugin.

This plugin will extract modules from any entry bundle into any number of arbitrarily defined smaller bundles

Why?

• Browsers will open between 6 and 10 parallel connections to a single host. By splitting up one large file (your main bundle) into a number of smaller ones, you can leverage these connections to download the files faster.
• It's likely that you will have some third party scripts which you change infrequently. By putting these into their own bundle, then if they haven't changed between builds, your users may still be able to use the cached version from before.

How?

Configuration of the plugin is simple. You instantiate the plugin with a single array of objects (lets call them buckets) with the keys name and test. Any modules which are in your entry chunk which match the bucket's regular expression inside test (first matching bucket is used), are then moved to a new chunk with the given name.

Further limiting can be achieved using the options only (whitelist) and except (blacklist). They both accept either a single or an array of entry bundle names.

Creating a 'catch-all' bucket is not necessary: anything which doesn't match one of the defined buckets will be left in the original chunk.

Example

var ExtractModulesPlugin = require('extract-modules-webpack-plugin');
module.exports = {
  entry: {
    app: 'app.js',
    frameworks: 'frameworks.js'
  },
  output: {
    path: __dirname + '/public',
    filename: "[name]-[chunkhash].js",
    chunkFilename: "[name]-[chunkhash].js"
  },
  plugins: [
    new ExtractModulesPlugin([{
        name: 'vendor',
        test: /vendor\//,
        except: 'frameworks'
      }, {
        name: 'views',
        test: /views\//,
        only: 'app'
    }])
  ]
};

An an example structure of modules included in the entry chunk:

/lib
    /views
        /list.js
        /grid.js
    /url.js
/vendor
    /jquery.js
    /backbone.js
/views
    /home.js
    /banner.js
/app.js
/frameworks.js (requires vendor/backbone.js)

The output would be three files:

• app-[hash].js, containing:
  • app.js
  • lib/url.js
• vendor-[hash].js, containing:
  • vendor/jquery.js
• frameworks-[hash].js, containing:
  • vendor/backbone.js
• views-[hash].js, containing:
  • lib/views/list.js
  • lib/views/grid.js
  • views/home.js
  • views/banner.js