@babel/plugin-transform-class-properties

What is @babel/plugin-transform-class-properties?

The @babel/plugin-transform-class-properties npm package allows developers to use the class properties syntax in JavaScript. It transforms static and instance properties so that they can be used in environments that do not support this feature natively.

What are @babel/plugin-transform-class-properties's main functionalities?

Static Class Properties

This feature allows you to define static properties on a class, which are properties that belong to the class itself rather than to instances of the class.

class MyClass { static myStaticProp = 42; }

Instance Class Properties

This feature enables you to define properties directly on class instances, with an initial value, without needing to set them inside the class constructor.

class MyClass { myInstanceProp = 'default value'; }

Other packages similar to @babel/plugin-transform-class-properties

@babel/plugin-proposal-class-properties

This package is a successor to @babel/plugin-transform-class-properties and includes the proposal for class properties as it moves through the TC39 process. It offers similar functionality but aligns with the latest proposal spec.

@babel/plugin-proposal-private-methods

While not identical, this package provides functionality for handling private methods and accessors in classes, which is related to the class fields feature that @babel/plugin-transform-class-properties handles.

@babel/preset-env

This package includes @babel/plugin-transform-class-properties as one of the plugins it might use to transform code. It provides a broader range of transformations based on the target environment's ECMAScript feature support.

README

@babel/plugin-transform-class-properties

This plugin transforms static class properties as well as properties declared with the property initializer syntax

See our website @babel/plugin-transform-class-properties for more information.

Install

Using npm:

npm install --save-dev @babel/plugin-transform-class-properties

or using yarn:

yarn add @babel/plugin-transform-class-properties --dev

Changelog

v7.27.1 (2025-04-30)

:eyeglasses: Spec Compliance

• babel-parser
  • #17254 Allow using of as lexical declaration within for (@JLHwung)
  • #17230 Disallow get/set in TSPropertySignature (@JLHwung)
• babel-parser, babel-types
  • #17193 Stricter TSImportType options parsing (@JLHwung)

:bug: Bug Fix

• babel-plugin-proposal-destructuring-private, babel-plugin-proposal-do-expressions, babel-traverse
  • #17137 fix: do expressions should allow early exit (@kermanx)
• babel-helper-wrap-function, babel-plugin-transform-async-to-generator
  • #17251 Fix: propagate argument evaluation errors through async promise chain (@magic-akari)
• babel-helper-remap-async-to-generator, babel-plugin-transform-async-to-generator
  • #17231 fix apply()/call() annotated as pure (@Lacsw)
• babel-helper-fixtures, babel-parser
  • #17233 Create ChainExpression within TSInstantiationExpression (@JLHwung)
• babel-generator, babel-parser
  • #17226 Fill optional AST properties when both estree and typescript parser plugin are enabled (Part 2) (@JLHwung)
• babel-parser
  • #17224 Fill optional AST properties when both estree and typescript parser plugin are enabled (Part 1) (@JLHwung)
  • #17080 Fix start of TSParameterProperty (@JLHwung)
• babel-compat-data, babel-preset-env
  • #17228 Update firefox bugfix compat data (@JLHwung)
• babel-traverse
  • #17156 fix: Objects and arrays with multiple references should not be evaluated (@liuxingbaoyu)
• babel-generator
  • #17216 Fix: support const type parameter in generator (@JLHwung)

:nail_care: Polish

• babel-plugin-bugfix-v8-spread-parameters-in-optional-chaining, babel-plugin-proposal-decorators, babel-plugin-transform-arrow-functions, babel-plugin-transform-class-properties, babel-plugin-transform-destructuring, babel-plugin-transform-object-rest-spread, babel-plugin-transform-optional-chaining, babel-plugin-transform-parameters, babel-traverse
  • #17221 Reduce generated names size for the 10th-11th (@nicolo-ribaudo)

:house: Internal

• babel-runtime-corejs2, babel-runtime-corejs3, babel-runtime
  • #17263 Remove unused regenerator-runtime dep in @babel/runtime (@nicolo-ribaudo)
• babel-compat-data, babel-preset-env
  • #17256 Tune plugin compat data (@JLHwung)
• babel-compat-data, babel-standalone
  • #17236 migrate babel-compat-data build script to mjs (@JLHwung)
• Other
  • #17232 Bump typescript-eslint to 8.29.1 (@JLHwung)
  • #17219 test: add basic typescript-eslint integration tests (@JLHwung)
  • #17205 Inline regenerator in the relevant packages (@nicolo-ribaudo)
• babel-register
  • #16844 Migrate @babel/register to cts (@liuxingbaoyu)
• babel-cli, babel-compat-data, babel-core, babel-generator, babel-helper-compilation-targets, babel-helper-fixtures, babel-helper-module-imports, babel-helper-module-transforms, babel-helper-plugin-test-runner, babel-helper-transform-fixture-test-runner, babel-helpers, babel-node, babel-parser, babel-plugin-transform-modules-amd, babel-plugin-transform-modules-commonjs, babel-plugin-transform-modules-systemjs, babel-plugin-transform-modules-umd, babel-plugin-transform-react-display-name, babel-plugin-transform-regenerator, babel-plugin-transform-runtime, babel-plugin-transform-typeof-symbol, babel-plugin-transform-typescript, babel-preset-env, babel-register, babel-standalone, babel-types
  • #17207 Enforce node protocol import (@JLHwung)
• babel-plugin-transform-regenerator
  • #17205 Inline regenerator in the relevant packages (@nicolo-ribaudo)
  • #17205 Inline regenerator in the relevant packages (@nicolo-ribaudo)
• babel-helpers, babel-plugin-transform-async-generator-functions, babel-plugin-transform-regenerator, babel-preset-env, babel-runtime-corejs3
  • #17205 Inline regenerator in the relevant packages (@nicolo-ribaudo)
• babel-helpers, babel-plugin-transform-regenerator
  • #17205 Inline regenerator in the relevant packages (@nicolo-ribaudo)
  • #17205 Inline regenerator in the relevant packages (@nicolo-ribaudo)
• babel-helpers
  • #17205 Inline regenerator in the relevant packages (@nicolo-ribaudo)

:microscope: Output optimization

• babel-helpers, babel-plugin-transform-modules-commonjs, babel-runtime-corejs3
  • #16538 Reduce interopRequireWildcard size (@liuxingbaoyu)
• babel-helpers, babel-plugin-transform-async-generator-functions, babel-plugin-transform-regenerator, babel-preset-env, babel-runtime-corejs3
  • #17213 Reduce regeneratorRuntime size (@liuxingbaoyu)