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https://github.com/louisbrunner/exist-utils
Utility functions that emulate CoffeeScript existence operator
https://github.com/louisbrunner/exist-utils
coffee coffee-script coffeescript elvis exists utils
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Utility functions that emulate CoffeeScript existence operator
- Host: GitHub
- URL: https://github.com/louisbrunner/exist-utils
- Owner: LouisBrunner
- License: mit
- Created: 2017-04-05T11:58:47.000Z (over 7 years ago)
- Default Branch: main
- Last Pushed: 2023-10-18T07:47:06.000Z (about 1 year ago)
- Last Synced: 2024-04-14T19:43:16.027Z (7 months ago)
- Topics: coffee, coffee-script, coffeescript, elvis, exists, utils
- Language: JavaScript
- Homepage:
- Size: 1.79 MB
- Stars: 0
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# exist-utils [![NPM Version][npm-image]][npm-url] ![Build Status][ci-image] [![Coverage Status][coveralls-image]][coveralls-url] [![dependencies Status][deps-image]][deps-url] [![devDependencies Status][deps-dev-image]][deps-dev-url]
This package is a collection of util functions that emulate _CoffeeScript_ existence operator.
While waiting that some of them are integrated in the [next version of JavaScript](https://github.com/tc39/proposals), you can use this package while porting from _CoffeeScript_, etc.
## Installation
### Node Installation
```sh
npm install exist-utils
```
You can then `ExistUtils = require('exist-utils')` or `import * as ExistUtils from 'exist-utils'`.
### Browser Installation
Use the minified UMD build in the `dist` folder: [here](dist/exist-utils.min.js).
It exports a global `window.ExistUtils` when imported as a `` tag.
## Usage
Each function as a full name (i.e. `exists`) and a shorthand (i.e. `ex`), both are specified in the title of their description.
You can check the equivalence with _CoffeeScript_ operators in the [following section](#coffeescript-equivalents).
### `exists` (`ex`)
Example:
```js
if (!exists(arg)) {
error('missing arg');
}
```
This is the equivalent to _CoffeeScript_ `val?`, it checks if a value "exists" (is neither `null` nor `undefined`).
### `existsChained` (`exc`)
Example:
```js
if (!existsChained(arg, 'callback')) {
error('no callback specified');
}
```
This is the equivalent to _CoffeeScript_ `obj?.prop?`, it checks if a whole chain "exists".
### `existsChainedValue` (`excv`)
Example:
```js
const callback = existsChainedValue(arg, 'callback');
if (!exists(callback)) {
error('no callback specified');
return;
}
callback();
```
This is the equivalent to _CoffeeScript_ `obj?.prop`, it checks if a whole chain "exists" and returns the final value.
### `elvis` (`el`)
Example:
```js
val = elvis(arg, 42);
```
This is the equivalent to _CoffeeScript_ `val ? default` and a safer version to `val || default`.
It returns the second value if the first one doesn't "exist".
### `callsIfExist` (`fnex`)
Example:
```js
callsIfExist(func, 1, 2);
```
This is the equivalent to _CoffeeScript_ `func?(1, 2)`, it checks the existence of the function and calls it with the provided arguments.
### `callsIfExistObj` (`fnexo`)
Example:
```js
callsIfExistObj(obj, 'func', 1, 2);
```
This is the equivalent to _CoffeeScript_ `obj?.func?(1, 2)`, it checks the existence of the function and calls it with the provided arguments while providing the right value for `this`.
## _CoffeeScript_ equivalents
| CoffeeScript | `exist-utils` | `exist-utils` shorthand |
|:-------------------------|:-----------------------------------|:---------------------------|
| `val?` | `exists(val)` | `ex(val)` |
| `obj?.prop?` | `existsChained(obj, 'prop')` | `exc(obj, 'prop')` |
| `obj?.prop` | `existsChainedValue(obj, 'prop')` | `excv(obj, 'prop')` |
| `val = arg ? 3` | `val = elvis(arg, 3)` | `val = el(arg, 3)` |
| `func?(a, b)` | `callsIfExist(func, a, b)` | `fnex(func, a, b)` |
| `obj.func?(a, b)` | `callsIfExistObj(obj, func, a, b)` | `fnexo(obj, func, a, b)` |
## License
MIT, Copyright (c) 2017-2020 Louis Brunner
[npm-image]: https://img.shields.io/npm/v/exist-utils.svg
[npm-url]: https://npmjs.org/package/exist-utils
[ci-image]: https://github.com/LouisBrunner/exist-utils/workflows/Build/badge.svg
[coveralls-image]: https://coveralls.io/repos/github/LouisBrunner/exist-utils/badge.svg?branch=master
[coveralls-url]: https://coveralls.io/github/LouisBrunner/exist-utils?branch=master
[deps-image]: https://david-dm.org/louisbrunner/exist-utils/status.svg
[deps-url]: https://david-dm.org/louisbrunner/exist-utils
[deps-dev-image]: https://david-dm.org/louisbrunner/exist-utils/dev-status.svg
[deps-dev-url]: https://david-dm.org/louisbrunner/exist-utils?type=dev