We all know that localStorage does not actively delete and will never be destroyed, so how to set the expiration time of localStorage?Let’s try it together today!
<script type=”text/javascript”>
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(‘ message has expired ‘);
// alert (” overdue information “)
} else {
// console log (” data = “+ dataObj. Data);
// the console. The log (JSON. Parse (dataObj. Data));
var dataObjDatatoJson = json.parse (dataobj.data)
return dataObjDatatoJson;}}
</script>

usage scenario:
1. Use local data to reduce network transmission
2. Weak network environment, high latency, low bandwidth, try to localize the data
Usage:
< script>
window.onload = function(){
var Ipt = document.getElementById(‘input1’);
var value = ‘{” name “:” and send the bore is clear “, “Age” : “18”, “address” : “lujiazui city”} “;
set (‘ information, value);
Function (){
//var dataObjData=get(‘information’,1000);
//var dataObjData=get(‘information’,1000*60);
//var dataObjData=get(‘information’,1000*60*60);
// expiration time is 1 hour// var Obj = get (” information “, 1000 * 60 * 60 * 24);
var dataObjData=get(‘information’,1000*60* 24*7);
console.log(dataObjData || null);
if (dataObjData! =”” & & dataObjData! . = null) {
the console log (” name: “+ dataObjData. Name);
the console. The log (” Age: “+ dataObjData. Age);
the console. The log (” address: “+ dataObjData. Age);
} else {
alert (” access to information has expired “);
}
}
}
< /script>

1 function setLocalStorage(key, value) {
 2     var curtime = new Date().getTime(); // Get the current time and convert it to a JSON string sequence. 
 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: Local Storage Exceeds Limit");
12             localStorage.clear();
13         } else {
14             console.log("Error: Failure to save to local storage");
15         }*/
16         // Compatibility Writing
17         if(isQuotaExceeded(e)) {
18             console.log("Error: Local Storage Exceeds Limit");
19             localStorage.clear();
20         } else {
21             console.log("Error: Failure to save to local storage");
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; // Seconds of the day
49     if(localStorage.getItem(key)) {
50         var vals = localStorage.getItem(key); // Get locally stored values 
51         var dataObj = JSON.parse(vals); // Converting Strings to JSON Objects
52         // If (current time - the time the stored element was set at creation) > Expiration time 
53         var isTimed = (new Date().getTime() - dataObj.timer) > exp;
54         if(isTimed) {
55             console.log("Storage has expired");
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);