設置localStorage的過時時間

 1 function setLocalStorage(key, value) {
 2     var curtime = new Date().getTime(); // 獲取當前時間 ，轉換成JSON字符串序列 
 3     var valueDate = JSON.stringify({
 4         val: value,
 5         timer: curtime
 6     });
 7     try {
 8         localStorage.setItem(key, valueDate);
 9     } catch(e) {
10         /*if(e.name === 'QUOTA_EXCEEDED_ERR' || e.name === 'NS_ERROR_DOM_QUOTA_REACHED') {
11             console.log("Error: 本地存儲超過限制");
12             localStorage.clear();
13         } else {
14             console.log("Error: 保存到本地存儲失敗");
15         }*/
16         // 兼容性寫法
17         if(isQuotaExceeded(e)) {
18             console.log("Error: 本地存儲超過限制");
19             localStorage.clear();
20         } else {
21             console.log("Error: 保存到本地存儲失敗");
22         }
23     }
24 }
25 
26 function isQuotaExceeded(e) {
27     var quotaExceeded = false;
28     if(e) {
29         if(e.code) {
30             switch(e.code) {
31                 case 22:
32                     quotaExceeded = true;
33                     break;
34                 case 1014: // Firefox 
35                     if(e.name === 'NS_ERROR_DOM_QUOTA_REACHED') {
36                         quotaExceeded = true;
37                     }
38                     break;
39             }
40         } else if(e.number === -2147024882) { // IE8 
41             quotaExceeded = true;
42         }
43     }
44     return quotaExceeded;
45 }
46 
47 function getLocalStorage(key) {
48     var exp = 60 * 60 * 24; // 一天的秒數
49     if(localStorage.getItem(key)) {
50         var vals = localStorage.getItem(key); // 獲取本地存儲的值 
51         var dataObj = JSON.parse(vals); // 將字符串轉換成JSON對象
52         // 若是(當前時間 - 存儲的元素在建立時候設置的時間) > 過時時間 
53         var isTimed = (new Date().getTime() - dataObj.timer) > exp;
54         if(isTimed) {
55             console.log("存儲已過時");
56             localStorage.removeItem(key);
57             return null;
58         } else {
59             var newValue = dataObj.val;
60         }
61         return newValue;
62     } else {
63         return null;
64     }
65 }
66 
67 setLocalStorage('name', 'hello, world');
68 var localKey = getLocalStorage('name');
69 console.log(localKey);