/webpack 1

List Of Hints


Not every hint apply to all apps. Some hints have positive and negative effects so it depends on your needs.

Hints are ordered by importance (most important comes first), but importance heavily depends on the app.

Hints are categorized by App, Developer and/or Build performance. Sometimes multiple categories apply.

App performance: Your app perform better. This affects the user of your app and/or the cost of serving the app to the user.

Developer performance: This makes it easier for your developers to write the app.

Build performance: The build of your app is faster and/or more stable.

App performance

  • Minimize your bundle with the UglifyJsPlugin (App, for every app)
  • Use Code Splitting: improves initial download size, at the cost of more requests (App, for big apps)
    • Hint for React apps: Use the react-proxy-loader
  • Add hashes to output files and enable Long Caching time on server: improves times for second visit (App, for every app)
    • Hint: Use records to keep module/chunk ids as consistent as possible
    • Hint for static HTML pages: Use the html-webpack-plugin
  • Don’t delete no longer used assets immediately after they are no longer used. Wait a few weeks before deleting them from server. Result: No 404s for users that keep browser windows open for long time (App, for every app)
  • Use the DefinePlugin to pass configuration from config to app: Embedded into bundle, Conditional code is removed with minimized (App, for apps with configuration)
    • Use the EnvironmentPlugin to pass process.env from build to app
  • Check bundle stats with analyse tool for problems: Improve total download size, Improve cohesion (App/Developer, for big apps)
    • Hint: Use the stats-webpack-plugin or the --json CLI option to get the stats
    • Hint: Use the profile option to gather more performance stats
  • Extract common modules into separate script file: improves caching for switching between pages, at the cost of additional requests for the initial page (App, for app with multiple entry points)
  • Remove duplication with npm dedupe/npm 4 and the DedupePlugin: improve total download size (App, for app using npm)
  • Do CSS processing with webpack: (App/Developer, for every app)
    • static assets (font/image/…) processing with webpack. (for every app)
      • inline static assets with the url-loader: improves time to initial view (by reducing roundtrips), at the cost of total download size (for every app)
    • Separate CSS file with the extract-text-webpack-plugin: eliminates FOUC for prerendered markup, improves time to initial view (by parallizing CSS and JS downloading) (for app with many CSS or prerendered content)
  • Fit the chunking to your needs via many Code Splitting Points and the chunk optimization plugins (LimitChunkCountPlugin, MinChunkSizePlugin, AggressiveMergingPlugin, )
  • Preload additional chunks by adding a script tag and deferring the chunk load: Faster initial view (App, for routed apps)

Developer performance

  • Use a configuration file (webpack.config.js) instead of passing CLI options: Easier to maintain, more options (Developer, for every app)
  • Don’t rewrite incompatible JS, but use imports-loader/exports-loader to make it compatible: Easier to upgrade to new version (Developer, for every app)
  • Use webpack devtools for debugging in browser: Better debugging experience, real source code, real module names, at the cost of slower build and difference to production build (Developer, for every app)
  • Write modules with ES6 module syntax: This is more future proof and allows more advanced optimizations (Developer/App/Build, for every app)
    • Current Status: Use the babel-loader to transform ES6 module syntax to CommonJS
    • Future: webpack 2 understand ES6 module syntax
    • Future: webpack enables advanced optimizations
  • Use output.library to build libraries that export stuff (Developer, for libraries)
  • Use externals to declare dependencies of your bundle on the target environment (Developer, for libraries and apps)
  • Enable Hot Module Replacement (HMR) for faster page updates (Developer, for every app)
    • Hint for React apps: Use the react-hot-loader or react-transform
    • Hint for CSS: Use the style-loader (without extract-text-webpack-plugin) for HMR
    • Hint for custom routers: Write custom handlers for updates at least at router level
  • Use Javascript in webpack config to share common configuration etc. (Developer, for every app)
  • Use resolve.root to configure a path to your app modules: Allows shorter references to dependencies (Developer, for big apps)
  • Use karma with karma-webpack to test modules in the browser (Developer, for every app)
  • Use target to build for other environments than the browser (Developer, for non-browser apps)
  • Use the BannerPlugin to add comments to the output assets: Licensing (Developer, for libraries)
  • Use debug to switch loaders to debug mode which provide more debug information (if the loader supports it): Better debugging experience (Developer, for every app)
  • Use include instead of exclude in module.loaders: less error prone and easier to add paths (Developer, for every app)

Build performance

  • Use incremental compilation: faster second build (Build, for every app)
    • Hint: Switch watching to polling with the watchOptions.poll option only if watching over network or inside of VMs
  • Use in-memory compilation for development build: faster build, less disk usage, at the cost of memory usage (Build, for every app)
    • Hint: Use the webpack-dev-server
  • Use multiple entry points instead of running webpack multiple times: Faster build, entry points can share chunks (Build/App, for multi page apps)
  • Pass an array of configurations to webpack to compile them in parallel while sharing disk cache and watchers: Faster builds and rebuilds, less problems with too many watchers (Build, for big apps with multiple configurations)
  • Use module.noParse for big CommonJS files without dependencies: Faster build times (Build, for app with these modules)


Feel free to add more hints to any category. If you were to add it or in which order you can add it to the Unsorted section and some more experienced user will pick it up.

© 2012–2015 Tobias Koppers
Licensed under the MIT License.