@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

v7.25.9 (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)