Babel Pure Top-Level Functions Plugin

A high-performance Babel plugin written in Rust to annotate top-level function calls with /*#__PURE__*/ comment for better tree-shaking and optimization.

Requirements

Rust

• Rust Edition: 2021
• Minimum Rust Version: 1.67.0
• Recommended Rust Toolchain: Stable (latest)

Node.js

• Minimum Version: 16.x
• Recommended Version: 18.x or 20.x

Package Managers

• npm
• yarn
• pnpm (Recommended)

Installation

Using pnpm (recommended):

pnpm add -D babel-plugin-pure-toplevel

Using npm:

npm install --save-dev babel-plugin-pure-toplevel

Using yarn:

yarn add -D babel-plugin-pure-toplevel

Usage

Babel Configuration

.babelrc

{
  "plugins": [
    "babel-plugin-pure-toplevel"
  ]
}

Programmatic Usage

import babel from '@babel/core';
import pureTopLevelPlugin from 'babel-plugin-pure-toplevel';

const result = babel.transform(code, {
  plugins: [pureTopLevelPlugin()]
});

Example

Input

function test() {
  Object.create({});
  new Date();
}

Output

function test() {
  /*#__PURE__*/Object.create({});
  /*#__PURE__*/new Date();
}

Features

• ✅ Annotate top-level function calls
• ✅ Skip TypeScript helper functions
• ✅ Skip function calls with arguments
• ✅ Support for CallExpression and NewExpression
• 🚀 High-performance Rust implementation

Development

Build Plugin

# Build for release
pnpm build

# Build for debug
pnpm build:debug

Run Tests

# Rust tests
pnpm test

# Babel integration tests (to be implemented)
pnpm test:babel

Performance

This plugin is implemented in Rust, providing near-native performance for AST transformations.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

MIT License

Acknowledgements

Inspired by Angular's pure annotation strategy and leveraging the power of Rust and SWC.