typedArray.entries

arr.entries()

var arr = new Uint8Array([10, 20, 30, 40, 50]);
var eArray = arr.entries();
// your browser must support for..of loop
// and let-scoped variables in for loops
for (let n of eArray) {
  console.log(n);
}

var arr = new Uint8Array([10, 20, 30, 40, 50]);
var eArr = arr.entries();
console.log(eArr.next().value); // [0, 10]
console.log(eArr.next().value); // [1, 20]
console.log(eArr.next().value); // [2, 30]
console.log(eArr.next().value); // [3, 40]
console.log(eArr.next().value); // [4, 50]