typedArray.findIndex

typedarray.findIndex(callback[, thisArg])

function isPrime(element, index, array) {
  var start = 2;
  while (start <= Math.sqrt(element)) {
    if (element % start++ < 1) {
      return false;
    }
  }
  return element > 1;
}

var uint8 = new Uint8Array([4, 6, 8, 12]);
var uint16 = new Uint16Array([4, 6, 7, 12]);

console.log(uint8.findIndex(isPrime)); // -1, not found
console.log(uint16.findIndex(isPrime)); // 2

TypedArray.prototype.findIndex = Array.prototype.findIndex = Array.prototype.findIndex || function(evaluator, thisArg) {
????????'use strict';
????????if (!this) {
??????????throw new TypeError('Array.prototype.some called on null or undefined');
????????}
????
????????if (typeof(evaluator) !== 'function') {
????????????if (typeof(evaluator) === 'string') {
????????????????// Attempt to convert it to a function
????????????????if ( ! (evaluator = eval(evaluator)) ){
????????????????????throw new TypeError();
????????????????}
????????????} else {
????????????????throw new TypeError();
????????????}
????????}
????????
????????var i;
????????if (thisArg === undefined) { ?// Optimize for thisArg
????????????for (i in this) {
????????????????if (evaluator(this[i], i, this)) {
????????????????????return i;
?????????? ?????}
???????? ???}
????????????return -1;
???? ???}
????????for (i in this) {
????????? ??if (evaluator.call(thisArg, this[i], i, this)) {
??????????? ??? return i;
?????????? ?}
????????}
????????return -1;
};