array.lastIndexOf()

Get the index of the last Array element that matches a provided value.

Signature

lastIndexOf(element: A) => Number | Null

lastIndexOf(element: A, end: Number) => Number | Null

Description

Searches, right-to-left, for the first element that matches a provided value and returns the index of the element if a match is found.

If an optional end index is provided, the method searches right-to-left starting at the end index and returns the first matching index (inclusive).

Parameters

Parameter Type Required Description

element

Generic

Yes

Value to search for in the Array elements.

start

Number

Starting index (inclusive) of the right-to-left search. Must be an Int.

Return value

One of:

Type Description

Number

Index of the element that matches the provided value.

Null

Returned if a match isn’t found.

Examples

['a', 'b', 'c', 'b'].lastIndexOf('c')
2

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