Sieve of Eratosthenes algorithm in JavaScript running endless for large number

Question

I have been trying to write Sieve of Eratosthenes algorithm in JavaScript. Basically I just literally followed the steps below:

1. Create a list of consecutive in

Answer 1

function sieveOfEratosthenes(num, fromSt = null) {
let boolArr = Array(num + 1).fill(true); // Taking num+1 for simplicity
boolArr[0] = false;
boolArr[1] = false;

for (
    let divisor = 2;
    divisor * divisor <= num;
    divisor = boolArr.indexOf(true, divisor + 1)
)
    for (let j = 2 * divisor; j <= num; j += divisor) boolArr[j] = false;

let primeArr = [];
for (
    let idx = fromSt || boolArr.indexOf(true);
    idx !== -1;
    idx = boolArr.indexOf(true, idx + 1)
)
    primeArr.push(idx);

return primeArr;
}