JS獲取兩個日期之間相差的天數

// JS獲取兩個日期之間相差的天數
function getDaysBetween(dateString1, dateString2) {
  var startDate = Date.parse(dateString1)
  var endDate = Date.parse(dateString2)
  var days = (endDate - startDate) / (1 * 24 * 60 * 60 * 1000)
  return days
}