is_leap_year.js

function isLeapYear(year) {
  var result = false;
  var yearVal = parseInt(year);
  if (yearVal % 100 == 0) {
    if (yearVal % 400 == 0) {
      result = true;
    }
  } else {
    if (yearVal % 4 == 0) {
      result = true;
    }
  }

  return result;
}