Prime Palindrome

Prime Palindrome

var highEnd = 1000;
var primes = sieve(highEnd);
highEnd--;
var found = false;
while (found == false ) {
    if (isPalindrome(highEnd.toString()) == true) {
        if (primes[highEnd] == true) {
            found = true;
        }
    }
    highEnd--;
}
console.log(++highEnd);
function isPalindrome(input) {
    var i;
    var length = input.length -1;

    for (i=0; i< length; i++) {
        if (input[i] != input[length-i]) {
            return false;
        }
    }
   return true;
}
function sieve (highEnd) {
    var sieve = newFilledArray(highEnd, true);
    var maxCheck = Math.sqrt(highEnd);
    var i, j;
    var results = [];

    for (i = 2; i <= maxCheck; i++) {
        if (sieve[i] == true) {
            for (j = i * i; j < highEnd; j += i) {
                sieve[j] = false
            }
        }
    }
    for (i=2; i<highEnd; i++) {
        if  (sieve[i]==true) {
            results.push(i);
        }
    }
    return(sieve);
}
function newFilledArray(length, val) {
    var array = [];
    for (var i = 0; i < length; i++) {
        array[i] = val;
    }
    return array;
}