Arrays.first()

added in 0.0.1 • updated in 0.5.0 • last revisions

Syntax

function first<T>(iterable: Iterable<T>): T | undefined

Returns the first element in an iterable. If the iterable is empty, returns undefined.

Parameters
`iterable`	An iterable with 0 or more elements from which the “0th” element is returned (but not removed).

Example

import { Arrays } from 'potence';

Arrays.first([3, 1, 5]);           // -> 3
Arrays.first(new Set([3, 1, 5]));  // -> 3

Remarks

When passing in an array, the behaviour is functionally equivalent to calling array[0].

When passing in any other iterable, this function calls its iterator and returns the first item yielded. It then discards the iterator without iterating over the remaining items, so the time complexity of this function is O(1) in all cases.

Compare Arrays.last().