Array.prototype.lastIndexOf()

const animals = ["Dodo", "Tiger", "Penguin", "Dodo"];

console.log(animals.lastIndexOf("Dodo"));
// : 3

console.log(animals.lastIndexOf("Tiger"));
// : 1

lastIndexOf(searchElement)
lastIndexOf(searchElement, fromIndex)

const numbers = [2, 5, 9, 2];
numbers.lastIndexOf(2); // 3
numbers.lastIndexOf(7); // -1
numbers.lastIndexOf(2, 3); // 3
numbers.lastIndexOf(2, 2); // 0
numbers.lastIndexOf(2, -2); // 0
numbers.lastIndexOf(2, -1); // 3

const array = [NaN];
array.lastIndexOf(NaN); // -1

const indices = [];
const array = ["a", "b", "a", "c", "a", "d"];
const element = "a";
let idx = array.lastIndexOf(element);
while (idx !== -1) {
  indices.push(idx);
  idx = idx > 0 ? array.lastIndexOf(element, idx - 1) : -1;
}

console.log(indices);
// [4, 2, 0]

console.log([1, , 3].lastIndexOf(undefined)); // -1

const arrayLike = {
  length: 3,
  0: 2,
  1: 3,
  2: 2,
  3: 5, // length  3  lastIndexOf() 
};
console.log(Array.prototype.lastIndexOf.call(arrayLike, 2));
// 2
console.log(Array.prototype.lastIndexOf.call(arrayLike, 5));
// -1