@babel/plugin-transform-react-pure-annotations

What is @babel/plugin-transform-react-pure-annotations?

The @babel/plugin-transform-react-pure-annotations package is a Babel plugin designed to enhance optimization for React components by automatically annotating React components with `/*#__PURE__*/` comments. These comments signal to JavaScript bundlers and minifiers, such as Terser, that the component functions can be safely tree-shaken if they are not used. This can lead to smaller bundle sizes in production builds.

What are @babel/plugin-transform-react-pure-annotations's main functionalities?

Automatic Pure Annotation for Functional Components

Automatically adds pure annotations to functional React components, indicating that they can be safely removed if unused.

Before:
const MyComponent = () => <div>Hello World</div>;

After:
const MyComponent = /*#__PURE__*/() => <div>Hello World</div>;

Automatic Pure Annotation for Class Components

Automatically adds pure annotations to the return value of render methods in class components, aiding in their potential tree-shaking.

Before:
class MyComponent extends React.Component {
  render() {
    return <div>Hello World</div>;
  }
}

After:
class MyComponent extends React.Component {
  render() {
    return /*#__PURE__*/<div>Hello World</div>;
  }
}

Other packages similar to @babel/plugin-transform-react-pure-annotations

@babel/plugin-transform-react-inline-elements

Transforms React.createElement calls to object literals. This can improve performance by reducing the overhead of these calls at runtime. However, it does not specifically focus on tree-shaking like @babel/plugin-transform-react-pure-annotations does.

@babel/plugin-transform-react-constant-elements

Hoists element creation to the highest scope possible. This can improve performance in React applications by reducing the need to recreate the same elements on each render. While it optimizes performance, its approach is different from adding pure annotations for tree-shaking.

README

@babel/plugin-transform-react-pure-annotations

Mark top-level React method calls as pure for tree shaking

See our website @babel/plugin-transform-react-pure-annotations for more information.

Install

Using npm:

npm install --save-dev @babel/plugin-transform-react-pure-annotations

or using yarn:

yarn add @babel/plugin-transform-react-pure-annotations --dev

Changelog

v7.25.9 (2024-10-22)

:bug: Bug Fix

• babel-parser, babel-template, babel-types
  • #16905 fix: Keep type annotations in syntacticPlaceholders mode (@liuxingbaoyu)
• babel-helper-compilation-targets, babel-preset-env
  • #16907 fix: support BROWSERSLIST{,_CONFIG} env (@JLHwung)
• Other
  • #16884 Analyze ClassAccessorProperty to prevent the no-undef rule (@victorenator)

:house: Internal

• babel-helper-transform-fixture-test-runner
  • #16914 remove test options flaky (@JLHwung)

:running_woman: Performance

• babel-parser, babel-types
  • #16918 perf: Make VISITOR_KEYS etc. faster to access (@liuxingbaoyu)