2から順に素数を表示するプログラム Javascript

<label for="numPrimes">表示する素数の個数:</label>
<input type="number" id="numPrimes" min="1" value="10"> <button onclick="displayPrimeNumbers()">表示する</button>
 <div id="primeNumbers"></div>

function isPrime(num) {
    if (num <= 1) return false;
    if (num <= 3) return true;
    if (num % 2 === 0 || num % 3 === 0) return false;
    let i = 5;
    while (i * i <= num) {
        if (num % i === 0 || num % (i + 2) === 0) return false;
        i += 6;
    }
    return true;
}

function displayPrimeNumbers() {
    let numPrimesInput = document.getElementById("numPrimes");
    let numPrimes = parseInt(numPrimesInput.value);

    let primes = [];
    let num = 2;

    while (primes.length < numPrimes) {
        if (isPrime(num)) {
            primes.push(num);
        }
        num++;
    }

    let primeNumbersDiv = document.getElementById("primeNumbers");
    primeNumbersDiv.innerHTML = "最初の" + numPrimes + "個の素数: " + primes.join(", ");
}