Project Euler Problem 4

peuler4.js

Array.prototype.max = function() {
	var max = this[0];
	var len = this.length;
	for (var i = 0; i < len; i++) {
		if (this[i] > max) {
			max = this[i];
		}
	}
	return max;
}

String.prototype.reverse = function() {
	return this.split("").reverse().join("");
}


var pal = [],
	b,
	a,
	ans,
	strans,
	l,
	h,
	strans1,
	strans2;

for(b = 999; b > 0; b--) {
	for(a = 999; a > 0; a--) {
		ans = b * a;
		strans = ans.toString();
		
		if(strans.length % 2 === 0) {
			l = strans.length / 2
			strans1 = strans.substr(0,l);
			strans2 = strans.substr(l);

			if(strans2 === strans1.reverse()) {
				pal.push(ans);
			}
		} else if(strans.length % 2 !== 0) {
			h = Math.floor(strans.length/2);
			strans1 = strans.substr(0,h);
			strans2 = strans.substr(h+1);

			if(strans2 === strans1.reverse()) {
				pal.push(ans);
			}
		}
	}
}

console.log(pal.max()); //gives 906609