Prime Number

isPrime.js

function isPrime(n) {
    let counter = 0;
    if (n == 2) return true;
    if (n % 2 == 0 || n == 1) return false;
    for (let i = 1; i <= n / 2; i += 2) {
        if (n % i == 0)
            counter++;
        if (counter == 2)
            break;
    }
    if (counter == 1)
        return true;
    return false;
}