npm package: @fav/type.is-empty
Description: Checks whether a value is empty or not.
Author: Takayuki Sato
Latest version: 1.0.2

# [@fav/type.is-empty][repo-url] [![NPM][npm-img]][npm-url] [![MIT License][mit-img]][mit-url] [![Build Status][travis-img]][travis-url] [![Build Status][appveyor-img]][appveyor-url] [![Coverage status][coverage-img]][coverage-url]

Checks whether a value is empty or not.

> "fav" is an abbreviation of "favorite" and also the acronym of "for all versions".
> This package is intended to support all Node.js versions and many browsers as possible.
> At least, this package supports Node.js >= v0.10 and major Web browsers: Chrome, Firefox, IE11, Edge, Vivaldi and Safari.

## Install

To install from npm:

```sh
$ npm install --save @fav/type.is-empty
```

***NOTE:*** *npm < 2.7.0 does not support scoped package, but old version Node.js supports it. So when you use such older npm, you should download this package from [github.com][repo-url], and move it in `node_modules/@fav/type.is-empty/` directory manually.*


## Usage

For Node.js:

```js
var isEmpty = require('@fav/type.is-empty');

isEmpty([]); // => true
isEmpty(['a']); // => false
isEmpty.not([]); // => false
isEmpty.not(['a']); // => true

isEmpty({}); // => true
isEmpty({ a: 1 }); // => false
isEmpty.not({}); // => false
isEmpty.not({ a: 1 }); // => true
```

For Web browsers:

```html
<script src="fav.type.is-empty.min.js"></script>
<script>
var isEmpty = fav.type.isEmpty;
isEmpty([]); // => true
isEmpty.not([]); // => false
</script>
```


## API

### <u>isEmpty(value) : boolean</u>

Checks if *value* is empty.

Definition of "empty" is different by data type.

* **undefined:** always empty.
* **null:** always empty.
* **array:** empty if it has no element.
* **plain object:** empty if it has no property. 
* **NodeList:** empty if it has no element.
* **HTMLCollection:** empty if it has no element.
* <i>**others:**</i> always not empty.

> This function always returns false for other collections like Map, Set, typed-array and so on, because I think there are few needs to check them without knowing their data types. If data type of a collection is known, its own API to get size of itself should be used.

#### Parameter:

| Parameter |  Type  | Description             |
|-----------|:------:|-------------------------|
| value     | *any*  | The value to be checked |

#### Return:

True, if *value* is empty.

**Type:** boolean


### <u>isEmpty.not(value) : boolean</u>

Checks if *value* is not empty.

This function always returns a negative boolean of `isEmpty(value)`.

#### Parameter:

| Parameter |  Type  | Description             |
|-----------|:------:|-------------------------|
| value     | *any*  | The value to be checked |

#### Return:

True, if *value* is not empty.

**Type:** boolean


## Checked                                                                      

### Node.js (4〜)

| Platform  |   4    |   5    |   6    |   7    |   8    |   9    |   10   |
|:---------:|:------:|:------:|:------:|:------:|:------:|:------:|:------:|
| macOS     |&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|
| Windows10 |&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|
| Linux     |&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|

### io.js (1〜3)

| Platform  |   1    |   2    |   3    |
|:---------:|:------:|:------:|:------:|
| macOS     |&#x25ef;|&#x25ef;|&#x25ef;|
| Windows10 |&#x25ef;|&#x25ef;|&#x25ef;|
| Linux     |&#x25ef;|&#x25ef;|&#x25ef;|

### Node.js (〜0.12)

| Platform  |  0.8   |  0.9   |  0.10  |  0.11  |  0.12  |
|:---------:|:------:|:------:|:------:|:------:|:------:|
| macOS     |&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|
| Windows10 |&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|
| Linux     |&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|&#x25ef;|

### Web browsers

| Platform  | Chrome | Firefox | Vivaldi | Safari |  Edge  | IE11   |
|:---------:|:------:|:-------:|:-------:|:------:|:------:|:------:|
| macOS     |&#x25ef;|&#x25ef; |&#x25ef; |&#x25ef;|   --   |   --   |
| Windows10 |&#x25ef;|&#x25ef; |&#x25ef; |   --   |&#x25ef;|&#x25ef;|
| Linux     |&#x25ef;|&#x25ef; |&#x25ef; |   --   |   --   |   --   |


## License

Copyright (C) 2017 Takayuki Sato

This program is free software under [MIT][mit-url] License.
See the file LICENSE in this distribution for more details.

[repo-url]: https://github.com/sttk/fav-type.is-empty/
[npm-img]: https://img.shields.io/badge/npm-v1.0.2-blue.svg
[npm-url]: https://www.npmjs.com/package/@fav/type.is-empty
[mit-img]: https://img.shields.io/badge/license-MIT-green.svg
[mit-url]: https://opensource.org/licenses/MIT
[travis-img]: https://travis-ci.org/sttk/fav-type.is-empty.svg?branch=master
[travis-url]: https://travis-ci.org/sttk/fav-type.is-empty
[appveyor-img]: https://ci.appveyor.com/api/projects/status/github/sttk/fav-type.is-empty?branch=master&svg=true
[appveyor-url]: https://ci.appveyor.com/project/sttk/fav-type-is-empty
[coverage-img]: https://coveralls.io/repos/github/sttk/fav-type.is-empty/badge.svg?branch=master
[coverage-url]: https://coveralls.io/github/sttk/fav-type.is-empty?branch=master