leapyears.js

function isALeapYear(year) {
  if (year % 400 === 0) return true;
  if (year % 100 === 0) return false;
  if (year % 4 === 0) return true;
}

function leapYears(number, year, years) {
  year = year || (new Date).getFullYear();
  years = years || [];
  if (isALeapYear(year)) years.push(year);
  return years.length >= number ? years : leapYears(number, ++year, years);
}

leaps = leapYears(100);
console.log(leaps);