1 var currentTime = Date.parse(new Date()); //当前时间戳
 2 var SetTimeStr = localStorage.getItem('SetTimeStr') * 1;
 3 var newTime = new Date().getTime() + 3600000 * 12;//新的过期时间
 4 if (currentTime < SetTimeStr) {
 5     console.log("缓存时间有效_");
 6     localStorage.setItem('SetTimeStr',newTime)
 7 } else { 8     localStorage.setItem('SetTimeStr',newTime)
 9 }