webpack-deadcode-plugin

0.1.17 verified Sat Apr 25 auth: no javascript

Webpack plugin (v0.1.17) that detects unused files and unused exports in used files during the webpack build process. It outputs warnings to the terminal without failing the build unless configured otherwise. Works with webpack 3, 4, and 5 via peer dependency. Key differentiators: supports both file and export detection, integrates with TypeScript loaders (with caveats), offers granular logging and JSON export. Active development with periodic releases.

Common errors

error Cannot find module 'webpack-deadcode-plugin' ↓

cause Package not installed or CommonJS require used in ESM module context.

fix

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

error TypeError: DeadCodePlugin is not a constructor ↓

cause Missing 'new' keyword or destructured import incorrectly.

fix

Use: const DeadCodePlugin = require('webpack-deadcode-plugin'); new DeadCodePlugin(options);

error Unused files not reported ↓

cause Patterns option too restrictive or exclude option incorrectly set.

fix

Ensure patterns match your source files, e.g., patterns: ['src/**/*.(js|jsx|ts|tsx|css)']

error Unused exports not detected when using babel ↓

cause Babel transforms modules and loses tracking. Need modules: false.

fix

Set modules: false in babel presets as described in documentation.

Warnings

gotcha When using babel-loader, must set modules: false in .babelrc or babel-loader options to prevent module transformation that would break dead code detection. ↓

fix In .babelrc: { "presets": [["env", { "modules": false }]] } or in webpack config: { loader: 'babel-loader', options: { presets: [['env', { modules: false }]] } }

gotcha With TypeScript loaders (ts-loader, awesome-typescript-loader), enabling transpileOnly/happyPackMode may produce incorrect output due to ts-loader issue #783. ↓

fix Disable transpileOnly or switch to awesome-typescript-loader for production.

breaking The plugin was originally designed for webpack 3 and 4; webpack 5 support was added in v0.1.13, but users must ensure version compatibility. ↓

fix Upgrade to v0.1.13 or later for webpack 5 compatibility.

gotcha The plugin outputs warnings only and does not fail the build by default. To fail on unused code, set failOnHint: true. ↓

fix Add failOnHint: true to options if you want the build to error out.

Install

npm install webpack-deadcode-plugin

yarn add webpack-deadcode-plugin

pnpm add webpack-deadcode-plugin

Imports

DeadCodePlugin
wrong
```
import DeadCodePlugin from 'webpack-deadcode-plugin';
```
correct
```
const DeadCodePlugin = require('webpack-deadcode-plugin');
```
Package uses CommonJS exports; ESM import may fail without a bundler. Use require() in Node.js or webpack config.
undefined
wrong
```
const { DeadCodePlugin } = require('webpack-deadcode-plugin');
```
correct
```
const DeadCodePlugin = require('webpack-deadcode-plugin');
```
The module exports a single constructor function directly, not as a named export. Destructuring will yield undefined.
DeadCodePlugin
wrong
```
DeadCodePlugin()
```
correct
```
new DeadCodePlugin({ ...options })
```
Must be called with 'new' and an options object; calling without 'new' will throw.

Quickstart

Basic webpack config with deadcode plugin to detect unused files/exports.

// webpack.config.js
const DeadCodePlugin = require('webpack-deadcode-plugin');

module.exports = {
  entry: './src/index.js',
  output: { filename: 'bundle.js' },
  plugins: [
    new DeadCodePlugin({
      patterns: ['src/**/*.(js|jsx|css)'],
      exclude: ['**/*.(stories|spec).(js|jsx)'],
      failOnHint: true,
    }),
  ],
};