localStorage设置存储时间

	function set(key,value){
		var curTime = new Date().getTime();
		localStorage.setItem(key,JSON.stringify({data:value,time:curTime}));
	}
	function get(key,exp){
		var data = localStorage.getItem(key);
		var dataObj = JSON.parse(data);
		if (new Date().getTime() - dataObj.time>exp) {
		    console.log('已过期');
		}else{
		    console.log('未过期');
    		var dataObjDatatoJson = JSON.parse(dataObj.data)
    		return dataObjDatatoJson;
		}
	}

注：该处设置的存储时间的单位为毫秒