var currentTime = Date.parse(new Date()); //当前时间戳
  var SetTimeStr = localStorage.getItem('SetTimeStr') * 1;
  var newTime = new Date().getTime() + 3600000 * 12;//新的过期时间
  if (currentTime < SetTimeStr) {
      console.log("缓存时间有效_");
      localStorage.setItem('SetTimeStr',newTime)
  } else { 
     localStorage.setItem('SetTimeStr',newTime)
 }