Array.prototype.findIndex

Returns the index of the first element in the array where predicate is true, and -1 otherwise.

Syntax

findIndex(predicate, thisArg?)

Return value

An index or -1 if the element is not found.

Parameters

• predicate function(value, index, array)

  A function that accepts up to three arguments. The findIndex method calls predicate once for each element of the array, in ascending order, until it finds one where predicate returns true. If such an element is found, findIndex immediately returns that element index. Otherwise, it returns -1.

• thisArg optional

  If provided, it will be used as the this value for each invocation of predicate. If it is not provided, undefined is used instead.