Triangle number check

gistfile1.txt

function isTriangleNumber(number) {
if (isNaN(number) || number != parseInt(number, 10)) return false;
else if (number == 0 || number == 1) return true;
else 

var m = (Math.sqrt(8*number+1) - 1) / 2;
if (m != parseInt(m,10)) return false;
else return true;
}