Finding Palindrome Number with js but problem with negative numbers

/**
 * @param {number} x
 * @return {boolean}
 */
var isPalindrome = function(x) {
    
  let a, b, c = 0;
    a = x%10;
    x=x-a;
    b= x/10;
    c= b%10;
    let d = b-c;
    let f = d/10;
    let g = (a*100) + (c*10) + f;
    if (g==x && x>0)
        return "true";
    else 
        return "false";
};

when the number is negative its not saying false, it says true instead. But i added x>0 condition. What’s the problem? And btw my code also doesn’t look good maybe it’s not a good way to solve the palindrome problem. And also i am not so sure if its working with numbers with more than 3 digits.