webpack-deadcode-plugin

Webpack Deadcode Plugin

Webpack plugin to detect unused files and unused exports in used files

Installation

Via npm:

$ npm install webpack-deadcode-plugin --save-dev

Via yarn:

$ yarn add -D webpack-deadcode-plugin

Usage

The plugin will report unused files and unused exports into your terminal but those are not part of your webpack build process, therefore, it will not fail your build (warning you). Simple add into your webpack config as follows:

✍️ If you use babel-loader, you have to set modules: false to make it works

# in .babelrc
{
  "presets": [
    ["env", { modules: false }]
  ]
}

# or in webpack.config.js -> module/rules
{
  loader: 'babel-loader',
  options: {
    presets: [
      ['env', { modules: false }]
    ]
  }
}

Webpack 3

const DeadCodePlugin = require('webpack-deadcode-plugin');

const webpackConfig = {
  ...
  plugins: [
    new DeadCodePlugin({
      patterns: [
        'src/**/*.(js|jsx|css)',
      ],
      exclude: [
        '**/*.(stories|spec).(js|jsx)',
      ],
    })
  ]
}

Webpack 4

const DeadCodePlugin = require('webpack-deadcode-plugin');

const webpackConfig = {
  ...
  optimization: {
    usedExports: true,
  },
  plugins: [
    new DeadCodePlugin({
      patterns: [
        'src/**/*.(js|jsx|css)',
      ],
      exclude: [
        '**/*.(stories|spec).(js|jsx)',
      ],
    })
  ]
}

Using non-existent css class names

To detect using non-existent class names in your codebase, you have to use es6-css-loader instead of style-loader/mini-css-extract-plugin. They are quite similiar in term of api except es6-css-loader supports to detect non-existent css class names.

You can check samples folder, how to to config webpack-deadcode-plugin and es6-css-loader.

Typescript

Using with typescript loader (ts-loader, awesome-typescript-loader), if you enable transpileOnly/happyPackMode, output might be not correct due to this issue. In case of incorrect output, the workaround solution is disabling transpileOnly, it will slow down webpack compiling time.

✍ Under some circumstances and production mode, if your output displays incorrect unused files, we encourage switching to awesome-typescript-loader.

Configuration

new DeadCodePlugin(options);

options.patterns (default: ["**/*.*"])

The array of patterns to look for unused files and unused export in used files. Directly pass to fast-glob

options.exclude (default: [])

The array of patterns to not look at.

options.context

Current working directory for patterns above. If you don't set it explicitly, your webpack context will be used.

options.failOnHint (default: false)

Deadcode does not interrupt the compilation by default. If you want to cancel the compilation, set it true, it throws a fatal error and stops the compilation.

options.detectUnusedFiles (default: true)

Whether to run unused files detection or not.

options.detectUnusedExport (default: true)

Whether to run unused export detection or not.

options.log (default: "all")

"all": show all messages.

"unused": only show messages when there are either unused files or unused export.

"none": won't show unused files or unused export messages in the terminal, it can keep terminal clean when set exportJSON to true

options.exportJSON (default: false)

false: won't create deadcode.json for the unused files and unused export.

true: create deadcode.json for the unused files and unused export at the root of the project.

You can set exportJSON to a specific path, and it will generate deadcode.json in that path.

new DeadCodePlugin({
  patterns: ["*.(js|css)"],
  exclude: ["**/node_modules/**"],
  log: "none",
  exportJSON: "./analysis"
}),