findIndex() method executes the
callbackFn function once for each element present in the typed array until it finds one where
callbackFn returns a true value. If such an element is found,
findIndex() immediately returns the index of that element. Otherwise,
findIndex() returns -1.
callbackFn is invoked only for indexes of the typed array which have assigned values; it is not invoked for indexes which have been deleted or which have never been assigned values.
callbackFn is invoked with three arguments: the value of the element, the index of the element, and the typed array object being traversed.
thisArg parameter is provided to
findIndex(), it will be used as the
this for each invocation of the
callback. If it is not provided, then
undefined is used.
findIndex() does not mutate the typed array on which it is called.
The range of elements processed by
findIndex() is set before the first invocation of
callbackFn. Elements that are appended to the typed array after the call to
findIndex() begins will not be visited by
callbackFn. If an existing, unvisited element of the typed array is changed by
callbackFn, its value passed to the visiting
callbackFn will be the value at the time that
findIndex() visits that element's index; elements that are deleted are not visited.