emit-changed-only-webpack-plugin

2.1.4 verified Sat Apr 25 auth: no javascript

Webpack production plugin that prevents identical output files from being re-emitted after a rebuild, preserving cache headers (ETag, Last-Modified) for unchanged assets. Current stable version 2.1.4 requires webpack ^4.0.0. Key differentiator: focuses on file emission behavior rather than chunk-level comparison, using [contenthash] to detect changes. Helps improve browser caching and V8 code caching by avoiding unnecessary file modifications. Ships TypeScript types.

Common errors

error TypeError: plugin is not a constructor ↓

cause Importing as ES module named import or using wrong require path.

fix

Use const EmitChangedOnlyPlugin = require('emit-changed-only-webpack-plugin');

error Cannot find module 'emit-changed-only-webpack-plugin' ↓

cause Package not installed or misspelled npm package name.

fix

npm install emit-changed-only-webpack-plugin --save-dev

error Error: Webpack mode must be 'production' ↓

cause Plugin enforces production mode by default.

fix

Set mode: 'production' or pass production: false in plugin options.

error Error: No output filename with [contenthash] found ↓

cause Output filename does not contain [contenthash].

fix

Add [contenthash] to output.filename, e.g., '[name].[contenthash].js'.

Warnings

gotcha Plugin requires [contenthash] in output filename; without it, file comparison is unreliable and plugin may emit all files every build. ↓

fix Add [contenthash] to output.filename, e.g., '[name].[contenthash].js'.

gotcha Production mode is enforced by default. If mode is not 'production', plugin will skip logic and may not behave as expected. ↓

fix Set mode: 'production' in webpack config, or pass production: false in plugin options.

gotcha The plugin removes outdated files in the output directory. Any files that are not produced by webpack and not excluded may be deleted. ↓

fix Add patterns to exclude option to protect non-plugin files, e.g., exclude: /\.(txt|png)$/i.

gotcha Using splitChunks: false will disable chunk splitting optimization; only the entry chunk is emitted. Default is true. ↓

fix If you want chunk splitting, keep splitChunks: true (default). Set to false only if you know you don't need it.

Install

npm install emit-changed-only-webpack-plugin

yarn add emit-changed-only-webpack-plugin

pnpm add emit-changed-only-webpack-plugin

Imports

EmitChangedOnlyPlugin
wrong
```
import EmitChangedOnlyPlugin from 'emit-changed-only-webpack-plugin'
```
correct
```
const EmitChangedOnlyPlugin = require('emit-changed-only-webpack-plugin')
```
Package is CommonJS only. ES module import will fail. If TypeScript, use `import EmitChangedOnlyPlugin = require(...)` or set `esModuleInterop`.

default

wrong

import { EmitChangedOnlyPlugin } from 'emit-changed-only-webpack-plugin'

correct

import EmitChangedOnlyPlugin from 'emit-changed-only-webpack-plugin'

Default export only. Named import does not exist.

EmitChangedOnlyPlugin
wrong
```
new EmitChangedOnlyPlugin()
```
correct
```
new EmitChangedOnlyPlugin({ exclude: /\.html$/i })
```
Always pass at least an options object; omitting may cause unexpected behavior with default options (e.g., production mode required).

Quickstart

Minimal webpack configuration using the plugin with contenthash filenames and an HTML exclusion pattern.

const EmitChangedOnlyPlugin = require('emit-changed-only-webpack-plugin');

module.exports = {
  output: {
    path: './dist',
    filename: '[name].[contenthash].js'
  },
  plugins: [
    new EmitChangedOnlyPlugin({
      exclude: /\.html$/i
    })
  ]
};