CODEWITHSUNDEEP
javascriptreactjswebpack
M Miller
M Miller

Reputation: 5642

Automatically loading externals with Webpack

I've done some searching but was wondering if there's an elegant solution here. When building a Webpack app, it's common to have dependencies that don't need to be compiled/bundled, like jQuery, React, ReactDOM, Angular, or Bootstrap, to name a few. You can list these in your Webpack config file in an externals object, but externals just assumes that these libraries will be available as namespaced globals at runtime.

This means that for each entry in your externals hash, you also need to toss in a script tag in your HTML. This makes sense if you're referencing an external CDN, but I'm thinking this could be automated if all you want to do is copy some dist file from a library in node_modules.

I've been looking for examples of how to do this but I haven't seen any yet. I messed with external-loader but I haven't had any luck integrating it (the documentation doesn't seem to provide a complete example).

Essentially, this would need to happen:

  1. Libraries that shouldn't be bundled should be added to resolve.alias, e.g. {"react": "react/dist/react.js"}
  2. A loader copies the dist files to the public directory (maybe this could just be done with file-loader?)
  3. An HTML loader or maybe plugin inserts the script tags before the bundle.js script tag

If something like this doesn't exist, I might look into trying to make one; I'm just posting this here to see if anyone might know of a pre-baked solution, as it seems like it'd be a common problem for building web apps and I figured I'm probably missing something.

Upvotes: 4

Views: 5466

Answers (3)

Matt B.
Matt B.

Reputation: 46

If you don't want to add extra package bloat then HtmlWebpackPlugin has templating features, so you could do something like this:

//template.html

<html>
  <head>
     <%= htmlWebpackPlugin.options.externals %>
  </head>
  ...
</html>

and then something like this in your webpack config:

//webpack.config.js

const EXTERNALS = [
  {
    name: 'react',
    globalVarName: 'React',
    src: 'https://cdn.example.com/react@18',
  },
  ...
]



module.exports = {
  ...,
  plugins: [
    new HtmlWebpackPlugin({
      filename: 'index.html',
      template: 'template.html',
      externals: EXTERNALS.reduce(
        (scripts, external) => (
          `${scripts}<script src="${external.src}"></script>`
        ), ''
      )
    })
  ],
  externals: EXTERNALS.reduce(
    (res, external) => ({
      ...res,
      [external.name]: external.globalVarName,
    }), {}
  ),
}

(You can obviously add any environment customisations/finer details/etc. you want in the webpack config file.)

EDIT:

For some extra panache you could also get the current package versions from your node_modules rather than hard-coding them into the webpack file:

const fs = require('fs')

function getPackageVersion(packageName) {
  const pkgPath = `node_modules/${packageName}`
  const pkg = JSON.parse(fs.readFileSync(`${pkgPath}/package.json`, 'utf8'))
  return pkg['version']
}

Upvotes: 0

coderman
coderman

Reputation: 1514

var path = require("path");
var webpack = require('webpack');
var HtmlWebpackPlugin = require('html-webpack-plugin');
var HtmlWebpackExternalsPlugin = require('html-webpack-externals-plugin');
var ExtractTextPlugin = require('extract-text-webpack-plugin');
var helpers = require('./helpers');

var WebpackNotifierPlugin = require('webpack-notifier');

module.exports = {
    entry: {
        'index-ref': './app/index-ref.ts',
        'vendor': './app/vendor.ts',
        'app': './app/main.ts',
    },

    resolve: {
        extensions: ['', '.ts', '.js']
    },

    module: {
        loaders: [
          {
              test: /\.ts$/,
              loaders: ['awesome-typescript-loader', 'angular2-template-loader']
          },
          {
              test: /\.html$/,
              loader: 'html'
          },
          {
              test: /\.(png|jpe?g|gif|svg|woff|woff2|ttf|eot|ico)$/,
              loader: 'file?name=assets/[name].[hash].[ext]'
          },
          {
              test: /\.css$/,
              exclude: helpers.root('app'),
              loader: ExtractTextPlugin.extract('style', 'css?sourceMap')
          },
          {
              test: /\.css$/,
              include: helpers.root('app'),
              loader: 'raw'
          }
        ]
    },

    plugins: [
      new webpack.optimize.CommonsChunkPlugin({
          name: ['app', 'vendor', 'index-ref']
      }),

      new HtmlWebpackPlugin({
          filename: '../index.html',
          template: 'template' + '/default.html',
          lib: ['jQuery'],
          chunks: ['entry-name']
      }),
      new HtmlWebpackExternalsPlugin([
        // Using a CDN for a JS library 
        {
            name: 'jquery',
            var: 'jQuery',
            url: 'https://cdnjs.cloudflare.com/ajax/libs/jquery/1.12.4/jquery.js'
        }
      ],
      {
          basedir: 'node_modules',
          dest: 'lib'
      }),

          new WebpackNotifierPlugin()
    ]
};

Am I missing anything here?

Upvotes: 2

M Miller
M Miller

Reputation: 5642

I didn't find a pre-existing solution, so I wrote a plugin to supplement the HtmlWebpackPlugin. It takes an array of externals and appends script/link tags to the HTML file, generates the externals hash, and can use CDNs or local files.

https://github.com/mmiller42/html-webpack-externals-plugin

Upvotes: 1

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