codeSnippet

isPrime.js

function isPrime(num) {
    var absNum = Math.abs(num);
    
    if (absNum <= 1) {
        return false;
    } else if (absNum <= 3) {
        return true;
    } else if (absNum % 2 === 0 || absNum % 3 === 0) {
        return false;
    }
    
    // The while loop takes into account numbers divisible by 5, 7, 11, 13 and 23
    var i = 5;
    while (i*i <= absNum) {
        if (absNum % i === 0 || absNum % (i + 2) === 0) return false;
        i += 6;
    }
    return true;
}