What is webpack?
Webpack is a powerful module bundler for JavaScript applications. It processes applications by internally building a dependency graph which maps every module your project needs and generates one or more bundles. It is highly extensible via loaders and plugins, and it's designed to manage, transform, and bundle frontend assets like JavaScript, CSS, and images.
What are webpack's main functionalities?
Module Bundling
Webpack bundles all the JavaScript files and other assets like CSS and images into a single output file. The code sample shows a basic webpack configuration defining an entry point and the output bundle.
module.exports = {
entry: './path/to/my/entry/file.js',
output: {
path: path.resolve(__dirname, 'dist'),
filename: 'my-first-webpack.bundle.js'
}
};
Loaders
Loaders allow webpack to process different types of files and convert them into modules that can be included in your bundle. The code sample demonstrates how to use loaders to handle .txt and .css files.
module.exports = {
module: {
rules: [
{ test: /\.txt$/, use: 'raw-loader' },
{ test: /\.css$/, use: ['style-loader', 'css-loader'] }
]
}
};
Plugins
Plugins can be leveraged to perform a wider range of tasks like bundle optimization, asset management, and environment variable injection. The code sample shows how to use the HtmlWebpackPlugin to generate an index.html file with the bundled assets injected.
const HtmlWebpackPlugin = require('html-webpack-plugin');
module.exports = {
plugins: [new HtmlWebpackPlugin({ template: './src/index.html' })]
};
Development Server
Webpack provides a development server that can be used to serve your application during development. It supports live reloading. The code sample configures the webpack development server to serve files from the 'dist' directory.
module.exports = {
devServer: {
contentBase: './dist',
open: true
}
};
Code Splitting
Code splitting allows you to split your code into various bundles which can then be loaded on demand or in parallel. The code sample shows how to split the application and vendor code into separate bundles.
module.exports = {
entry: {
app: './src/app.js',
vendor: './src/vendor.js'
},
output: {
filename: '[name].bundle.js',
path: __dirname + '/dist'
}
};
Other packages similar to webpack
rollup
Rollup is a module bundler for JavaScript which uses a flat bundle approach that's more efficient for libraries and applications with a complex module structure. It's known for its tree-shaking capabilities, which eliminate unused code.
parcel
Parcel is a web application bundler that offers a zero-configuration setup. It's known for its fast bundle times and out-of-the-box support for many file types without the need for additional plugins or loaders.
browserify
Browserify lets you require('modules') in the browser by bundling up all of your dependencies. It's been around longer than webpack and has a simpler approach, but it lacks some of the more advanced features and optimizations that webpack offers.
fuse-box
FuseBox is a bundler/module loader that combines the power of webpack, JSPM, and SystemJS. It introduces a streamlined workflow and has a powerful API. It's known for its speed and simplicity.
Table of Contents
- Install
- Introduction
- Concepts
- Contributing
- Support
- Core Team
- Sponsoring
- Premium Partners
- Other Backers and Sponsors
- Gold Sponsors
- Silver Sponsors
- Bronze Sponsors
- Backers
- Special Thanks
Install
Install with npm:
npm install --save-dev webpack
Install with yarn:
yarn add webpack --dev
Introduction
Webpack is a bundler for modules. The main purpose is to bundle JavaScript
files for usage in a browser, yet it is also capable of transforming, bundling,
or packaging just about any resource or asset.
TL;DR
- Bundles ES Modules, CommonJS, and AMD modules (even combined).
- Can create a single bundle or multiple chunks that are asynchronously loaded at runtime (to reduce initial loading time).
- Dependencies are resolved during compilation, reducing the runtime size.
- Loaders can preprocess files while compiling, e.g. TypeScript to JavaScript, Handlebars strings to compiled functions, images to Base64, etc.
- Highly modular plugin system to do whatever else your application requires.
Get Started
Check out webpack's quick Get Started guide and the other guides.
Browser Compatibility
Webpack supports all browsers that are ES5-compliant (IE8 and below are not supported).
Webpack also needs Promise
for import()
and require.ensure()
. If you want to support older browsers, you will need to load a polyfill before using these expressions.
Concepts
Webpack has a rich plugin
interface. Most of the features
within webpack itself use this plugin interface. This makes webpack very
flexible.
Webpack enables the use of loaders to preprocess files. This allows you to bundle
any static resource way beyond JavaScript. You can easily write your own
loaders using Node.js.
Loaders are activated by using loadername!
prefixes in require()
statements,
or are automatically applied via regex from your webpack configuration.
Files
Name | Status | Install Size | Description |
---|
val-loader | ![val-npm](https://img.shields.io/npm/v/val-loader.svg) | ![val-size](https://packagephobia.com/badge?p=val-loader) | Executes code as module and considers exports as JS code |
JSON
Name | Status | Install Size | Description |
---|
![](https://worldvectorlogo.com/logos/coffeescript.svg) | ![cson-npm](https://img.shields.io/npm/v/cson-loader.svg) | ![cson-size](https://packagephobia.com/badge?p=cson-loader) | Loads and transpiles a CSON file |
Transpiling
Name | Status | Install Size | Description |
---|
![babel-loader](https://worldvectorlogo.com/logos/babel-10.svg) | ![babel-npm](https://img.shields.io/npm/v/babel-loader.svg) | ![babel-size](https://packagephobia.com/badge?p=babel-loader) | Loads ES2015+ code and transpiles to ES5 using Babel |
![](https://cdn.rawgit.com/Microsoft/TypeScript/master/doc/logo.svg) | ![type-npm](https://img.shields.io/npm/v/ts-loader.svg) | ![type-size](https://packagephobia.com/badge?p=ts-loader) | Loads TypeScript like JavaScript |
![](https://worldvectorlogo.com/logos/coffeescript.svg) | ![coffee-npm](https://img.shields.io/npm/v/coffee-loader.svg) | ![coffee-size](https://packagephobia.com/badge?p=coffee-loader) | Loads CoffeeScript like JavaScript |
Templating
Name | Status | Install Size | Description |
---|
![](https://worldvectorlogo.com/logos/html5.svg) | ![html-npm](https://img.shields.io/npm/v/html-loader.svg) | ![html-size](https://packagephobia.com/badge?p=html-loader) | Exports HTML as string, requires references to static resources |
![](https://cdn.rawgit.com/pugjs/pug-logo/master/SVG/pug-final-logo-_-colour-128.svg) | ![pug-npm](https://img.shields.io/npm/v/pug-loader.svg) | ![pug-size](https://packagephobia.com/badge?p=pug-loader) | Loads Pug templates and returns a function |
![](https://worldvectorlogo.com/logos/markdown.svg) | ![md-npm](https://img.shields.io/npm/v/markdown-loader.svg) | ![md-size](https://packagephobia.com/badge?p=markdown-loader) | Compiles Markdown to HTML |
![](https://posthtml.github.io/posthtml/logo.svg) | ![posthtml-npm](https://img.shields.io/npm/v/posthtml-loader.svg) | ![posthtml-size](https://packagephobia.com/badge?p=posthtml-loader) | Loads and transforms a HTML file using PostHTML |
![](https://worldvectorlogo.com/logos/handlebars-1.svg) | ![hbs-npm](https://img.shields.io/npm/v/handlebars-loader.svg) | ![hbs-size](https://packagephobia.com/badge?p=handlebars-loader) | Compiles Handlebars to HTML |
Styling
Name | Status | Install Size | Description |
---|
<style> | ![style-npm](https://img.shields.io/npm/v/style-loader.svg) | ![style-size](https://packagephobia.com/badge?p=style-loader) | Add exports of a module as style to DOM |
![](https://worldvectorlogo.com/logos/css-3.svg) | ![css-npm](https://img.shields.io/npm/v/css-loader.svg) | ![css-size](https://packagephobia.com/badge?p=css-loader) | Loads CSS file with resolved imports and returns CSS code |
![](https://worldvectorlogo.com/logos/less-63.svg) | ![less-npm](https://img.shields.io/npm/v/less-loader.svg) | ![less-size](https://packagephobia.com/badge?p=less-loader) | Loads and compiles a LESS file |
![](https://worldvectorlogo.com/logos/sass-1.svg) | ![sass-npm](https://img.shields.io/npm/v/sass-loader.svg) | ![sass-size](https://packagephobia.com/badge?p=sass-loader) | Loads and compiles a Sass/SCSS file |
![](https://worldvectorlogo.com/logos/stylus.svg) | ![stylus-npm](https://img.shields.io/npm/v/stylus-loader.svg) | ![stylus-size](https://packagephobia.com/badge?p=stylus-loader) | Loads and compiles a Stylus file |
![](https://worldvectorlogo.com/logos/postcss.svg) | ![postcss-npm](https://img.shields.io/npm/v/postcss-loader.svg) | ![postcss-size](https://packagephobia.com/badge?p=postcss-loader) | Loads and transforms a CSS/SSS file using PostCSS |
Frameworks
Name | Status | Install Size | Description |
---|
![](https://worldvectorlogo.com/logos/vue-9.svg) | ![vue-npm](https://img.shields.io/npm/v/vue-loader.svg) | ![vue-size](https://packagephobia.com/badge?p=vue-loader) | Loads and compiles Vue Components |
![](https://worldvectorlogo.com/logos/polymer.svg) | ![polymer-npm](https://img.shields.io/npm/v/polymer-webpack-loader.svg) | ![polymer-size](https://packagephobia.com/badge?p=polymer-webpack-loader) | Process HTML & CSS with preprocessor of choice and require() Web Components like first-class modules |
![](https://worldvectorlogo.com/logos/angular-icon-1.svg) | ![angular-npm](https://img.shields.io/npm/v/angular2-template-loader.svg) | ![angular-size](https://packagephobia.com/badge?p=angular2-template-loader) | Loads and compiles Angular 2 Components |
![](https://worldvectorlogo.com/logos/riot.svg) | ![riot-npm](https://img.shields.io/npm/v/riot-tag-loader.svg) | ![riot-size](https://packagephobia.com/badge?p=riot-tag-loader) | Riot official webpack loader |
Performance
Webpack uses async I/O and has multiple caching levels. This makes webpack fast
and incredibly fast on incremental compilations.
Module Formats
Webpack supports ES2015+, CommonJS and AMD modules out of the box. It performs clever static
analysis on the AST of your code. It even has an evaluation engine to evaluate
simple expressions. This allows you to support most existing libraries out of the box.
Webpack allows you to split your codebase into multiple chunks. Chunks are
loaded asynchronously at runtime. This reduces the initial loading time.
Webpack can do many optimizations to reduce the output size of your
JavaScript by deduplicating frequently used modules, minifying, and giving
you full control of what is loaded initially and what is loaded at runtime
through code splitting. It can also make your code chunks cache
friendly by using hashes.
Contributing
We want contributing to webpack to be fun, enjoyable, and educational for anyone, and everyone. We have a vibrant ecosystem that spans beyond this single repo. We welcome you to check out any of the repositories in our organization or webpack-contrib organization which houses all of our loaders and plugins.
Contributions go far beyond pull requests and commits. Although we love giving you the opportunity to put your stamp on webpack, we also are thrilled to receive a variety of other contributions including:
- Documentation updates, enhancements, designs, or bugfixes
- Spelling or grammar fixes
- README.md corrections or redesigns
- Adding unit, or functional tests
- Triaging GitHub issues -- especially determining whether an issue still persists or is reproducible.
- Searching #webpack on twitter and helping someone else who needs help
- Teaching others how to contribute to one of the many webpack's repos!
- Blogging, speaking about, or creating tutorials about one of webpack's many features.
- Helping others in our webpack gitter channel.
To get started have a look at our documentation on contributing.
If you are worried or don't know where to start, you can always reach out to Sean Larkin (@TheLarkInn) on Twitter or simply submit an issue and a maintainer can help give you guidance!
We have also started a series on our Medium Publication called The Contributor's Guide to webpack. We welcome you to read it and post any questions or responses if you still need help.
Looking to speak about webpack? We'd love to review your talk abstract/CFP! You can email it to webpack [at] opencollective [dot] com and we can give pointers or tips!!!
Creating your own plugins and loaders
If you create a loader or plugin, we would <3 for you to open source it, and put it on npm. We follow the x-loader
, x-webpack-plugin
naming convention.
Support
We consider webpack to be a low-level tool used not only individually but also layered beneath other awesome tools. Because of its flexibility, webpack isn't always the easiest entry-level solution, however we do believe it is the most powerful. That said, we're always looking for ways to improve and simplify the tool without compromising functionality. If you have any ideas on ways to accomplish this, we're all ears!
If you're just getting started, take a look at our new docs and concepts page. This has a high level overview that is great for beginners!!
Looking for webpack 1 docs? Please check out the old wiki, but note that this deprecated version is no longer supported.
If you want to discuss something or just need help, here is our Gitter room where there are always individuals looking to help out!
If you are still having difficulty, we would love for you to post
a question to StackOverflow with the webpack tag. It is much easier to answer questions that include your webpack.config.js and relevant files! So if you can provide them, we'd be extremely grateful (and more likely to help you find the answer!)
If you are twitter savvy you can tweet #webpack with your question and someone should be able to reach out and help also.
If you have discovered a 🐜 or have a feature suggestion, feel free to create an issue on Github.
License
![FOSSA Status](https://app.fossa.io/api/projects/git%2Bhttps%3A%2F%2Fgithub.com%2Fwebpack%2Fwebpack.svg?type=large)
Core Team
Most of the core team members, webpack contributors and contributors in the ecosystem do this open source work in their free time. If you use webpack for a serious task, and you'd like us to invest more time on it, please donate. This project increases your income/productivity too. It makes development and applications faster and it reduces the required bandwidth.
This is how we use the donations:
- Allow the core team to work on webpack
- Thank contributors if they invested a large amount of time in contributing
- Support projects in the ecosystem that are of great value for users
- Support projects that are voted most (work in progress)
- Infrastructure cost
- Fees for money handling
Premium Partners
Other Backers and Sponsors
Before we started using OpenCollective, donations were made anonymously. Now that we have made the switch, we would like to acknowledge these sponsors (and the ones who continue to donate using OpenCollective). If we've missed someone, please send us a PR, and we'll add you to this list.
Become a gold sponsor and get your logo on our README on Github with a link to your site.
Become a silver sponsor and get your logo on our README on Github with a link to your site.
Become a bronze sponsor and get your logo on our README on Github with a link to your site.
Backers
Become a backer and get your image on our README on Github with a link to your site.
![](https://opencollective.com/webpack/backer/100/avatar.svg?requireActive=false)
Special Thanks to
(In chronological order)