terser-loader

2.0.3 verified Sat Apr 25 auth: no javascript

terser-loader is a webpack loader that minifies JavaScript using Terser, a modern ES6+ capable minifier. Version 2.0.3 is the latest stable release, with peer dependency on webpack ^4 || ^5. It offers options like `terserOptions` passed directly to Terser API and `stripTrailingSemicolon`. Unlike the official `terser-webpack-plugin`, this is a loader (not a plugin) integrated in webpack's module rules pipeline, useful for selective minification alongside other loaders. Low release cadence but functional for specific use cases.

Common errors

error Module not found: Error: Can't resolve 'terser' ↓

cause Missing Terser peer dependency

fix

Install terser as a dev dependency: npm install --save-dev terser

error ValidationError: Invalid options object. Terser Loader has been initialized using an options object that does not match the API schema. ↓

cause Options passed are not recognized

fix

Check terserOptions for valid Terser options; do not use options like 'output' directly on the loader.

error Error: webpack <4 is not supported ↓

cause Using terser-loader@2 with webpack 3 or lower

fix

Upgrade webpack to version 4 or 5, or install terser-loader@1

Warnings

gotcha Loader is not a plugin; it runs on each module individually, not on the final bundle. Use terser-webpack-plugin for bundle-level minification. ↓

fix If you need bundle-level minification, use terser-webpack-plugin instead.

breaking Version 2.0.0 dropped support for webpack <4. ↓

fix Upgrade webpack to ^4 || ^5, or stick to terser-loader@1 for webpack 3.

deprecated The stripTrailingSemicolon option is non-standard and may be removed in future versions. ↓

fix Use terserOptions.output.semicolon = false instead.

Install

npm install terser-loader

yarn add terser-loader

pnpm add terser-loader

Imports

terser-loader
wrong
```
const TerserLoader = require('terser-loader');
```
correct
```
import TerserLoader from 'terser-loader';
```
ESM default import; CommonJS require works but not recommended for modern webpack configs if using ESM.

Quickstart

Configures terser-loader to minify all .js files, removing console.log and trailing semicolons. Use in production builds.

// webpack.config.js
const path = require('path');

module.exports = {
  entry: './src/index.js',
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'bundle.js',
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        use: [
          {
            loader: 'terser-loader',
            options: {
              terserOptions: {
                compress: {
                  drop_console: true,
                },
              },
              stripTrailingSemicolon: true,
            },
          },
        ],
      },
    ],
  },
  mode: 'production',
};