@babel/plugin-transform-parameters

What is @babel/plugin-transform-parameters?

The @babel/plugin-transform-parameters package is a Babel plugin that transforms function parameter features, such as default parameters, destructured parameters, and rest parameters, into ES5-compatible syntax. This transformation allows developers to use modern JavaScript features while maintaining compatibility with older environments that may not support these newer syntaxes natively.

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

Default Parameters

Transforms functions with default parameters to check for `undefined` and assign a default value if necessary. This allows for cleaner function signatures and easier parameter handling.

function log(message = 'Default message') { console.log(message); }

Destructured Parameters

Enables the use of destructuring in function parameters, transforming it into a series of variable assignments for compatibility. This simplifies the extraction of properties from objects passed as function arguments.

function greet({ name, age }) { console.log(`Hello ${name}, you are ${age} years old.`); }

Rest Parameters

Transforms rest parameters into a standard ES5 arguments pattern, allowing functions to accept an indefinite number of arguments as an array.

function concatenate(separator, ...strings) { return strings.join(separator); }

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

@babel/plugin-transform-destructuring

Similar to the destructuring aspect of @babel/plugin-transform-parameters, this plugin transforms destructuring assignments and rest/spread properties to ES5. However, it focuses more broadly on destructuring patterns outside of function parameters as well.

@babel/plugin-transform-spread

This plugin transforms spread elements into a form that can be understood by environments without native support for this syntax. While it deals with the spread operator like the rest parameters feature of @babel/plugin-transform-parameters, it's applied in array literals and function calls rather than function parameters.

README

@babel/plugin-transform-parameters

Compile ES2015 default and rest parameters to ES5

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

Install

Using npm:

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

or using yarn:

yarn add @babel/plugin-transform-parameters --dev

Changelog

v7.24.7 (2024-06-05)

:bug: Bug Fix

• babel-node
  • #16554 Allow extra flags in babel-node (@nicolo-ribaudo)
• babel-traverse
  • #16522 fix: incorrect constantViolations with destructuring (@liuxingbaoyu)
• babel-helper-transform-fixture-test-runner, babel-plugin-proposal-explicit-resource-management
  • #16524 fix: Transform using in switch correctly (@liuxingbaoyu)

:house: Internal

• babel-helpers, babel-runtime-corejs2, babel-runtime-corejs3, babel-runtime
  • #16525 Delete unused array helpers (@blakewilson)