Can someone please explain the output of this code for me?

Question

c3 : function(){
let arr = [1,2,3];
let str = 'abc';
let x = 1;
do {
arr[x] = str[arr[x]];
x++;
}
while(x<arr.length-1);
console.log(arr);
}

Now I know the output is an array with the items {1, "c", 3}
But I don't know why..

Answer 1

Do-while block take from array item with index x (second item, as x == 1) and sets it to third (as it takes 2 as index) letter of string. Then prints whole array.
Hope it helps.
Btw. Use better tags, for example: what language, issue, ...

Answer 2

The loop executes first without checking the condition (because its a do-while loop).
arr[1]=str[2]..
And then you increment x( now x=2)and the condition becomes false.Next you print the array

Answer 3

Ravindra Desai thanks for noticing, i forgot about this