`array.indexWhere()`

Get the index of an Array element that matches the given predicate.

Signature

indexWhere(predicate: () => Boolean | Null) => Number | Null

indexWhere(predicate: () => Boolean | Null, start: Number) => Number | Null

The indexWhere() method searches, left-to-right, for the element that matches predicate and returns the index of the element if a match is found.

If the optional start is included, predicate searches right-to-left starting at start and returns the matching index, inclusive.

Parameter	Type	Required	Description
predicate	Function	Yes	Function that tests for a matching element.
start	Number		Starting location of a right-to-left search.

Parameter

Type

Required

Description

predicate

Yes

Function that tests for a matching element.

start

Starting location of a right-to-left search.

Type Description

Type	Description
Number	Index of element that matches predicate or `null` if a match isn’t found.

Index of element that matches predicate or null if a match isn’t found.

['a', 'b', 'c', 'b'].indexWhere(v => v == 'c')

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