Type Guards

`Instances`

Type-gaurd methods for elements.

method	param	value
`isFile()`	target: `unknown`	target is a File
`isNode()`	target: `unknown`	target is a Node
`isElement()`	target: `unknown`	target is an Element
`isHTMLElement()`	target: `unknown`	target is a HTMLElement
`isHTMLInputElement()`	target: `unknown`	target is a HTMLInputElement
`isHTMLSelectElement()`	target: `unknown`	target is a HTMLSelectElement
`isHTMLTextAreaElement()`	target: `unknown`	target is a HTMLTextAreaElement
`isHTMLVideoElement()`	target: `unknown`	target is a HTMLVideoElement
`isHTMLAnchorElement()`	target: `unknown`	target is a HTMLAnchorElement
`isHTMLImageElement()`	target: `unknown`	target is a HTMLImageElement
`isHTMLOptionElement()`	target: `unknown`	target is a HTMLOptionElement
`isHTMLButtonElement()`	target: `unknown`	target is a HTMLButtonElement

Return value: `Boolean`

`isKeyOf()`

Check if a key is included in a readonly array

param	value
key: `string`	The main element
source: `readonly T[]`	Readonly array of strings

Return value: `Boolean`

Example

const keyToCheck = 'hello';

const arrayToCheck = ['hello', 'how', 'are', 'you'];

const isKeyPresent = isKeyOf(keyToCheck, arrayToCheck); // true

`isFormField()`

Checks if an element is a form field element

param	value
element: `Element / EventTarget / null`	element

Return value: `Boolean`

`isNotEmpty()`

This util makes sure there are no null or undefined in the passed value. Useful for type safety when filtering empty elements from an array.

param	value
value: `T / null / undefined`	value to check

Return value: `Boolean`

Example:

const items = [1, null, 4, undefined, 8];

const filteredItemsError: number[] = items.filter((item) => value !== undefined && value !== null); // Type '(number | null | undefined)[]' is not assignable to type 'number[]'.

const filteredItemsSuccess: number[] = items.filter(isNotEmpty); // Success!

`Primitives`

Type-gaurd methods for primitives

method	param	value
`isString()`	value: `unknown`	type of value is a string
`isNumber()`	value: `unknown`	type of value is a number
`isBigint()`	value: `unknown`	type of value is a bigint
`isBoolean()`	value: `unknown`	type of value is a boolean
`isSymbol()`	value: `unknown`	type of value is a symbol
`isUndefined()`	value: `unknown`	type of value is undefined
`isNull()`	value: `unknown`	type of value is null
`isFunction()`	value: `unknown`	type of value is a function
`isObject()`	value: `unknown`	type of value is an object

Return value: `Boolean`

Type Guards #

Instances #

isKeyOf() #

isFormField() #

isNotEmpty() #