babel-plugin-uglify

1.0.2 verified Sat Apr 25 auth: no javascript deprecated

Babel plugin that integrates UglifyJS minification directly into the Babel pipeline without needing to generate and re-parse code. v1.0.2 is the latest stable release. This plugin works on the Mozilla AST (SpiderMonkey format) used internally by Babel, avoiding repeated code generation and parsing. It is intended for Babel 5.x only, as Babel 6+ uses different AST formats. No longer actively maintained; alternatives include babel-minify (babili) or terser-based plugins. Key differentiator: direct AST-level minification preserves source maps and avoids overhead of stringifying and re-parsing code.

Common errors

error Couldn't find preset "es2015" relative to directory ↓

cause Missing Babel preset when trying to run transforms before uglify

fix

Install and configure Babel presets (e.g., babel-preset-es2015) in .babelrc or programmatic options.

error Unexpected token: name (x) ↓

cause Plugin ran before ES6 transformers, so UglifyJS encountered ES6 syntax

fix

Ensure plugin is specified with ':after' suffix (e.g., 'uglify:after') so it runs after ES6 transforms.

error require('babel').transform is not a function ↓

cause Using Babel 6+ API with babel-plugin-uglify which is only for Babel 5

fix

Use Babel 5 API (require('babel')) or switch to a Babel 6+ compatible minifier plugin.

Warnings

deprecated babel-plugin-uglify is deprecated. Babel 6+ does not use Mozilla AST, and this plugin is incompatible. Use babel-minify (babili) or plugins based on terser. ↓

fix Migrate to @babel/plugin-minify (babel-minify) or babel-plugin-terser.

breaking The plugin requires Babel 5.x. It will not work with Babel 6 or later due to AST format changes. ↓

fix Use Babel 5 or switch to a Babel 6+ compatible minifier.

gotcha The plugin must be specified with ':after' suffix (e.g., 'uglify:after') in Babel plugins list; otherwise it runs before ES6 transforms and UglifyJS will fail on ES6 syntax. ↓

fix Add ':after' suffix to plugin name in .babelrc or programmatic options.

deprecated UglifyJS itself is less actively maintained than terser. Consider using terser-based plugins for better ES6+ support and ongoing maintenance. ↓

fix Use babel-plugin-terser instead of babel-plugin-uglify.

Install

npm install babel-plugin-uglify

yarn add babel-plugin-uglify

pnpm add babel-plugin-uglify

Imports

plugin
wrong
```
{"plugins": ["uglify"]}
```
correct
```
// In .babelrc: {"plugins": ["uglify:after"]}
```
Must use ':after' suffix to ensure it runs after ES6 transforms. Without it, UglifyJS may receive untransformed ES6 code and fail.

Quickstart

Shows how to configure babel-plugin-uglify via .babelrc and Node API, including the required ':after' suffix.

// .babelrc example
{
  "plugins": ["uglify:after"]
}

// Node API example
var babel = require('babel');
babel.transform('const x = 1;', {
  plugins: ['uglify:after']
}, function(err, result) {
  console.log(result.code);
});