Find the largest palindrome made from the product of two 3-digit numbers - Javascript

Question

Can anyone tell me what\'s wrong with the code. Find the largest palindrome made from the product of two 3-digit numbers.

function largestPalind         


        

Answer 1

A bit more optimized version with comments included. Notice, there is no need of fast return, just store the max and optimize the cycles to not recalculate j*i if i*j has already been checked.

function largestPalindrome() {

    var max = 0;

    // not using i >= 100 since 100*100 is not palindrome! :)
    for (var i = 999; i > 100; i--) {
        // because i * j === j * i, no need of both i and j
        // to count down from 999
        for (var j = i; j > 100; j--) {
            var mul = j * i;
            if (isPalin(mul) && mul > max) {
                max = i * j;
            }
        }
    }

    return max;

}

function isPalin(i) {

    // adding empty string to i instead using of .toString
    // avoids unnecessary wrapping in String object on the left side
    i = '' + i;

    // don't rely on ==,  use === instead
    return i === i.split("").reverse().join("");

}

console.log(largestPalindrome());