babel-plugin-transform-nullish-operator [![NPM Version][npm-image]][npm-url] ![Build Status][ci-image] [![Coverage Status][coveralls-image]][coveralls-url]

This package is a babel plugin which can be used to emulate the Coffeescript existence operator (a?) in Babel using the new coalescing nullish operator (Stage 4 proposal).

This is completely non-standard, experimental and could break at any time.

Example

In

``javascript
var fooExists = object.foo ?? EXISTS;
`

Out

`javascript
var _object$foo;

var fooExists = (_object$foo = object.foo) !== null && _object$foo !== void 0;
`

> NOTE: We cannot use != null here because document.all == null and
> document.all has been deemed not "nullish".

Installation

`sh
npm install --save-dev babel-plugin-transform-nullish-operator
`

Usage

$3

`json
{
"plugins": ["babel-plugin-transform-nullish-operator"]
}
`

$3

`sh
babel --plugins babel-plugin-transform-nullish-operator script.js
`

$3

`javascript
require("@babel/core").transform("code", {
plugins: ["babel-plugin-transform-nullish-operator"]
});
`

Options

$3

string, defaults to EXISTS.

Can be used to change the identifier which is used to trigger this alternative behavior of the nullish coalescing operator.

#### Example with {"identifier": "DO_YOU_EXIST"}

In

`javascript
var fooExists = object.foo ?? DO_YOU_EXIST;
`

Out

`javascript
var _object$foo;

var fooExists = (_object$foo = object.foo) !== null && _object$foo !== void 0;
`

Linting

Your linter might EXISTS as undefined (which is true, the symbol doesn't actually exists, it is only a placeholder), in that case you will need to explicitely add it in your config.

Example using eslint:

`json
{
...
"globals": {
"EXISTS": "readonly"
},
...
}
`

References & Thanks

This is project is heavily based on Babel's @babel/plugin-proposal-nullish-coalescing-operator` (including code, tests, usage, etc).

License

MIT, Copyright (c) 2020-2020 Louis Brunner

[npm-image]: https://img.shields.io/npm/v/babel-plugin-transform-nullish-operator.svg
[npm-url]: https://npmjs.org/package/babel-plugin-transform-nullish-operator
[ci-image]: https://github.com/LouisBrunner/babel-plugin-transform-nullish-operator/workflows/Build/badge.svg
[coveralls-image]: https://coveralls.io/repos/github/LouisBrunner/babel-plugin-transform-nullish-operator/badge.svg?branch=main
[coveralls-url]: https://coveralls.io/github/LouisBrunner/babel-plugin-transform-nullish-operator?branch=main