获取日期相减总的天数

getDaysByDateString (dateString1, dateString2) {
  var startDate = Date.parse(dateString1.replace('/-/g', '/'))
  var endDate = Date.parse(dateString2.replace('/-/g', '/'))
  var diffDate = (endDate - startDate) + 1 * 24 * 60 * 60 * 1000
  var days = diffDate / (1 * 24 * 60 * 60 * 1000)
  return days
}