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https://github.com/louisbrunner/babel-plugin-transform-nullish-operator
A Babel plugin which emulates the `a?` existence check from CoffeeScript using the `??` syntax
https://github.com/louisbrunner/babel-plugin-transform-nullish-operator
babel babel-plugin coffeescript exists javascript
Last synced: 20 days ago
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A Babel plugin which emulates the `a?` existence check from CoffeeScript using the `??` syntax
- Host: GitHub
- URL: https://github.com/louisbrunner/babel-plugin-transform-nullish-operator
- Owner: LouisBrunner
- License: mit
- Created: 2020-10-16T11:18:47.000Z (about 4 years ago)
- Default Branch: main
- Last Pushed: 2024-06-12T11:08:29.000Z (5 months ago)
- Last Synced: 2024-10-13T15:23:05.081Z (24 days ago)
- Topics: babel, babel-plugin, coffeescript, exists, javascript
- Language: JavaScript
- Homepage: https://www.npmjs.com/package/babel-plugin-transform-nullish-operator
- Size: 1.65 MB
- Stars: 1
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# `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](https://babeljs.io/docs/en/next/babel-plugin-proposal-nullish-coalescing-operator.html) ([Stage 4 proposal](https://github.com/tc39/proposal-nullish-coalescing)).
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$foo !== void 0;
```
> **NOTE:** We cannot use `!= null` here because `document.all == null` and
> `document.all` has been deemed not "nullish".
## Installation
```sh
npm install --save-dev babel-plugin-transform-nullish-operator
```
## Usage
### With a configuration file (Recommended)
```json
{
"plugins": ["babel-plugin-transform-nullish-operator"]
}
```
### Via CLI
```sh
babel --plugins babel-plugin-transform-nullish-operator script.js
```
### Via Node API
```javascript
require("@babel/core").transform("code", {
plugins: ["babel-plugin-transform-nullish-operator"]
});
```
## Options
### `identifier`
`string`, defaults to `EXISTS`.
Can be used to change the identifier which is used to trigger this alternative behavior of the nullish coalescing operator.
#### Example with `{"identifier": "DO_YOU_EXIST"}`
**In**
```javascript
var fooExists = object.foo ?? DO_YOU_EXIST;
```
**Out**
```javascript
var _object$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`](https://babeljs.io/docs/en/next/babel-plugin-proposal-nullish-coalescing-operator.html) (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