@babel/plugin-transform-runtime

What is @babel/plugin-transform-runtime?

The @babel/plugin-transform-runtime package is a Babel plugin that enables the re-use of Babel's injected helper code to save on codesize. It also allows you to use built-ins such as Promise or WeakMap, static methods like Array.from or Object.assign, instance methods like Array.prototype.includes, and generator functions in environments that do not natively support them.

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

Helpers

This feature allows Babel to transform code by extracting common helper functions into shared modules to reduce code duplication in the output.

"use strict";\n\nfunction _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError(\"Cannot call a class as a function\"); } }\n\nvar Foo = function Foo() {\n  _classCallCheck(this, Foo);\n};

Polyfills for instance methods

This feature enables the use of instance methods like 'includes' on arrays, which are part of the ECMAScript specifications but may not be available in all environments.

import \"core-js/stable\";\nimport \"regenerator-runtime/runtime\";\n\n[1, 2, 3].includes(2);

Built-ins

This feature allows the use of new built-in objects like Promise, which are part of the ECMAScript specifications but may not be natively supported in all environments.

import \"core-js/stable\";\nimport \"regenerator-runtime/runtime\";\n\nvar promise = new Promise();

Generator functions

This feature allows the use of generator functions, which can be used to perform asynchronous operations in a synchronous-like manner.

import \"core-js/stable\";\nimport \"regenerator-runtime/runtime\";\n\nfunction* aGenerator() {\n  yield 1;\n  yield 2;\n  yield 3;\n}

Other packages similar to @babel/plugin-transform-runtime

core-js

Core-js is a modular standard library for JavaScript, which includes polyfills for ECMAScript up to 2021. It's similar to @babel/plugin-transform-runtime in that it provides polyfills for features not available in older environments, but it's more comprehensive and can be used without Babel.

regenerator-runtime

Regenerator-runtime is a standalone runtime for Regenerator-compiled generator and async functions. It's similar to the generator function handling part of @babel/plugin-transform-runtime but does not include other transformations or helpers.

babel-polyfill

Babel-polyfill is now deprecated in favor of @babel/preset-env and core-js. It used to provide a full set of polyfills for Babel users. It was similar to @babel/plugin-transform-runtime but included the polyfills in the global scope, which could lead to conflicts.

README

@babel/plugin-transform-runtime

Externalise references to helpers and builtins, automatically polyfilling your code without polluting globals

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

Install

Using npm:

npm install --save-dev @babel/plugin-transform-runtime

or using yarn:

yarn add @babel/plugin-transform-runtime --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)