At its core, webpack is a static module bundler for modern JavaScript applications. When webpack processes your application, it internally builds a dependency graph from one or more entry points and then combines every module your project needs into one or more bundles, which are static assets to serve your content from.
Since version 4.0.0, webpack does not require a configuration file to bundle your project. Nevertheless, it is incredibly configurable to better fit your needs.
To get started you only need to understand its Core Concepts:
This document is intended to give a high-level overview of these concepts, while providing links to detailed concept-specific use cases.
For a better understanding of the ideas behind module bundlers and how they work under the hood, consult these resources:
An entry point indicates which module webpack should use to begin building out its internal dependency graph. Webpack will figure out which other modules and libraries that entry point depends on (directly and indirectly).
By default its value is ./src/index.js, but you can specify a different (or multiple entry points) by setting an entry property in the webpack configuration. For example:
webpack.config.js
module.exports = {
entry: './path/to/my/entry/file.js',
};
The output property tells webpack where to emit the bundles it creates and how to name these files. It defaults to ./dist/main.js for the main output file and to the ./dist folder for any other generated file.
You can configure this part of the process by specifying an output field in your configuration:
webpack.config.js
const path = require('path');
module.exports = {
entry: './path/to/my/entry/file.js',
output: {
path: path.resolve(__dirname, 'dist'),
filename: 'my-first-webpack.bundle.js',
},
};
In the example above, we use the output.filename and the output.path properties to tell webpack the name of our bundle and where we want it to be emitted to. In case you're wondering about the path module being imported at the top, it is a core Node.js module that gets used to manipulate file paths.
Out of the box, webpack only understands JavaScript and JSON files. Loaders allow webpack to process other types of files and convert them into valid modules that can be consumed by your application and added to the dependency graph.
At a high level, loaders have two properties in your webpack configuration: