firstIndex() Function

Returns the first index in array whose value satisfies the predicate.

Signature

export declare function firstIndex<T>(array: readonly T[], predicate: (value: T, index: number, array: readonly T[]) => boolean): number;

Parameter	Type	Description
array	readonly T[]	The array to search.
predicate	(value: T, index: number, array: readonly T[]) => boolean	A predicate. There should exist some index `I` such that `predicate(array[i])` returns true for all `i >= I` and returns false otherwise.
(Returns)	number	The first index in `array` whose value satisfies the `predicate`, or `-1` if no such index exists.