@bemoje/assert-type/readme.md

Perform easy type-checks with a simple type assertion.

# @bemoje/assert-type

Perform easy type-checks with a simple type assertion.

#### Version

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#### Travis CI

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#### Dependencies

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#### Stats

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## Installation

```sh
npm install @bemoje/assert-type
npm install --save @bemoje/assert-type
npm install --save-dev @bemoje/assert-type
```

## Usage

```javascript
import assertType from '@bemoje/assert-type'

/**
 * @param {string} str
 * @param {number} num
 * @param {null} nul
 * @param {number|string} strOrNum
 */
function example(str, num, nul, strOrNum) {
	// quite extensive, but now very simple type-checks.
	assertType(String, str)
	assertType(Number, num)
	assertType(null, nul)
	assertType([String, Number], strOrNum)

	// other code
	return 'Types are checked and OK'
}

const STRING = 'a'
const NUMBER = 1
const ARRAY = []

// NOTE: 'undefined' always passes type check

example()
//=> 'Types are checked and OK'

example(STRING, NUMBER, null, STRING)
//=> 'Types are checked and OK'

example(STRING, NUMBER, null, NUMBER)
//=> 'Types are checked and OK'

example(ARRAY, NUMBER, null, STRING)
//=> throws TypeError('Expected String, got Array')

example(STRING, ARRAY, null, STRING)
//=> throws TypeError('Expected Number, got Array')

example(STRING, NUMBER, ARRAY, STRING)
//=> throws TypeError('Expected Null, got Array')

example(STRING, NUMBER, null, ARRAY)
//=> throws TypeError('Expected String, Number, got Array')

```


## Tests
Uses *Jest* to test module functionality. Run tests to get coverage details.

```bash
npm run test
```

## API
### assertType

Perform easy type-checks with a simple type assertion.

##### Parameters

-   `constructors` **([function][3] | null | [Array][4]&lt;([function][3] | null)>)** The expected type's constructor(s). Also accepted as a "constructor" is the null value.

-   `value` **any** The value to evaluate

##### Returns
**void** 

[1]: #asserttype

[2]: #parameters

[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function

[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array