JS日期差，相差的天數

// 相差的天數
getDaysBetween: function(dateString1, dateString2) {
  var startDate = Date.parse(dateString1);
  var endDate = Date.parse(dateString2);
  var days =  Math.ceil((endDate - startDate) / (1 * 24 * 60 * 60 * 1000));
  return days;
},