@babel/plugin-transform-new-target

What is @babel/plugin-transform-new-target?

The @babel/plugin-transform-new-target npm package is designed to transform instances of the `new.target` meta-property within functions. This is particularly useful for compiling ES6 code to be compatible with environments that do not support the `new.target` syntax. The `new.target` property is used within constructors to determine if the constructor was called with the `new` operator, allowing constructors to identify how they were invoked and to behave differently if necessary.

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

Transforming new.target

This feature allows the transformation of `new.target` usage into a form that can be understood by environments that do not support this syntax. It checks if the constructor was called with `new` and throws an error if it wasn't, ensuring that the constructor behaves as intended even in older JavaScript environments.

function MyConstructor() {\n  if (!new.target) {\n    throw 'MyConstructor must be called with new';\n  }\n  console.log('MyConstructor was called with new');\n}\n// Transformed Code:\nfunction MyConstructor() {\n  var _newtarget = this instanceof MyConstructor ? this.constructor : void 0;\n  if (!_newtarget) {\n    throw 'MyConstructor must be called with new';\n  }\n  console.log('MyConstructor was called with new');\n}

Other packages similar to @babel/plugin-transform-new-target

@babel/plugin-transform-arrow-functions

Similar to @babel/plugin-transform-new-target, this package transforms ES6 arrow functions into function expressions that older JavaScript environments can understand. While it focuses on arrow functions rather than the `new.target` property, both plugins serve the purpose of making modern JavaScript code compatible with older environments.

@babel/plugin-transform-classes

This package transforms ES6 class syntax into equivalent ES5 constructor functions. Like @babel/plugin-transform-new-target, it deals with issues related to constructor functions and their invocation, ensuring that class-based code can run in environments that do not support the ES6 class syntax.

README

@babel/plugin-transform-new-target

Transforms new.target meta property

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

Install

Using npm:

npm install --save-dev @babel/plugin-transform-new-target

or using yarn:

yarn add @babel/plugin-transform-new-target --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)