kata.js

function isPrime(num) {
    if (num <= 1) return false;
    if (num % 2 === 0 && num > 2) return false;

    const sqrt = Math.sqrt(num);
    for (let i = 3; i <= sqrt; i += 2) {
        if (num % i === 0) return false;
    }

    return true;
}

console.log(isPrime(0));
//  false, "0 is not prime"

console.log(isPrime(1));
//  false, "1 is not prime"

console.log(isPrime(2));
//  true, "2 is prime"

console.log(isPrime(73));
// true, "73 is prime"

console.log(isPrime(75));
// false, "75 is not prime"

console.log(isPrime(-1));
// false, "-1 is not prime"

console.log(isPrime(3));
//  true, "3 is prime"

console.log(isPrime(5));
//  true, "5 is prime"

console.log(isPrime(7));
//  true, "7 is prime"

console.log(isPrime(41));
// true, "41 is prime"

console.log(isPrime(5099));
// true, "5099 is prime"

console.log(isPrime(4));
//  false, "4 is not prime"

console.log(isPrime(6));
//  false, "6 is not prime"

console.log(isPrime(8));
//  false, "8 is not prime"

console.log(isPrime(9));
// false, "9 is not prime"

console.log(isPrime(45));
// false, "45 is not prime"

console.log(isPrime(-5));
// false, "-5 is not prime"

console.log(isPrime(-8));
// false, "-8 is not prime"

console.log(isPrime(-41));
// false, "-41 is not prime"