@ava/babel-preset-stage-4

Babel preset for use with AVA

Aspires to bring finished ECMAScript proposals to AVA's test and helper files.

Efficiently applies the minimum of transforms to run the latest JavaScript syntax on Node.js 8, 10 and 12.

Built-ins are not added or extended, so features like Proxies, Array.prototype.includes or String.prototype.padStart will only be available if the Node.js version running the tests supports it. Consult node.green for details.

Sometimes a particular feature is mostly implemented in Node.js. In that case transforms are not applied.

Not all proposals can be supported via Babel transforms, see below for details. Babel may require "syntax" plugins in order to parse certain files. These plugins should be applied explicitly since this preset may not include them.

Install

$ npm install --save @ava/babel-preset-stage-4

Usage

Add @ava/stage-4 to your Babel presets.

Options

For more information on setting options for a preset, refer to the preset options documentation.

modules

By default this preset transform ES2015 modules to CommonJS. Set to false to disable this behavior. Other values are ignored.

Supported proposals

Proposal	Supported
Array.prototype.includes	No
Object.values/Object.entries	No
String padding	No
Object.getOwnPropertyDescriptors	No
Trailing commas in function parameter lists and calls	Yes
Shared memory and atomics	No
Lifting template literal restriction	No
s (dotAll) flag for regular expressions	Yes
RegExp named capture groups	No
RegExp Lookbehind Assertions	No
RegExp Unicode Property Escapes	No
Promise.prototype.finally	No
Asynchronous Iteration	Partially†
Optional catch binding	Yes
JSON superset	No
Symbol.prototype.description	No
Function.prototype.toString revision	No
Object.fromEntries	No
Well-formed JSON.stringify	No
String.prototype.{trimStart,trimEnd}	No
Array.prototype.{flat,flatMap}	No
String.prototype.matchAll	No
import()	Yes
Promise.allSettled	No

† @babel/plugin-proposal-async-generator-functions relies on Symbol.asyncIterator, which AVA does not polyfill for you.