原文网址：JS--localStorage设置过期时间的方案(有示例)_IT利刃出鞘的博客-CSDN博客
简介
说明
本文介绍如何使用localStorage设置数据的过期时间。
问题描述
localStorage是不支持设置过期时间的，cookie虽然支持设置过期时间但它存的数据量很小。所以在需要存一些带过期时间的数据时，就要手写工具来实现。
思路
存数据时：将value封装到一个对象里，这个对象里额外加一个过期时间。
读数据时：如果当前时间超过了过期时间，则返回null或者空对象；否则返回value。
测试结果
如下几种方案的测试结果都是一样的：
第一次获取时获取到了数据；4秒后数据过期了，再获取时成了null。
方案1：封装为函数
js
/*** 写入localStorage* @param key key* @param value value* @param expire 超时时间（以秒为单位）*/
function writeExpire(key, value, expire) {let obj = {time: new Date().getTime(),data: value,expire: expire,};let objStr = JSON.stringify(obj);localStorage.setItem(key, objStr);
}/*** 读出localStorage*/
function readExpire(key) {let value = localStorage.getItem(key);if (!value || value === "null") {return value;}value = JSON.parse(value);if (Date.now() - value.time > value.expire * 1000) {localStorage.removeItem(key);return null;}return value.data;
}
html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title><script src="LocalStorageUtil.js"></script>
</head>
<body>
<script>writeExpire("key1", "value1", 2)console.log(readExpire("key1"));sleep(4000).then(() => {console.log(readExpire("key1"));})function sleep(time) {return new Promise((resolve) => setTimeout(resolve, time));}
</script>
</body>
</html>方案2：封装为对象
js
export let localStorageUtil = {/*** 写入localStorage* @param key key* @param value value* @param expire 超时时间（以秒为单位）*/writeExpire: function (key, value, expire) {let obj = {time: new Date().getTime(),data: value,expire: expire,};let objStr = JSON.stringify(obj);localStorage.setItem(key, objStr);},/*** 读出localStorage*/readExpire: function (key) {let value = localStorage.getItem(key);if (!value || value === "null") {return value;}value = JSON.parse(value);if (Date.now() - value.time > value.expire * 1000) {localStorage.removeItem(key);return null;}return value.data;}
}// export default localStorageUtil;html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<script type="module">import {localStorageUtil} from "./LocalStorageUtil.js";localStorageUtil.writeExpire("key1", "value1", 2)console.log(localStorageUtil.readExpire("key1"));sleep(4000).then(() => {console.log(localStorageUtil.readExpire("key1"));})function sleep(time) {return new Promise((resolve) => setTimeout(resolve, time));}
</script>
</body>
</html>方案3：ES5扩展localStorage
js
/*** 写入localStorage* @param key key* @param value value* @param expire 超时时间（以秒为单位）*/
Storage.prototype.writeExpire = (key, value, expire) => {let obj = {data: value,time: Date.now(),expire: expire};//localStorage 设置的值不能是对象，转为json字符串localStorage.setItem(key, JSON.stringify(obj));
}/*** 读出localStorage*/
Storage.prototype.readExpire = key => {let value = localStorage.getItem(key);if (!value || value === "null") {return null;}val = JSON.parse(value);if (Date.now() - val.time > val.expire * 1000) {localStorage.removeItem(key);return null;}return val.data;
}
html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<script type="module">import './LocalStorageUtil.js';localStorage.writeExpire("key1", "value1", 2)console.log(localStorage.readExpire("key1"));sleep(4000).then(() => {console.log(localStorage.readExpire("key1"));})function sleep(time) {return new Promise((resolve) => setTimeout(resolve, time));}
</script>
</body>
</html>方案4：ES6扩展localStorage
js
class LocalStorageUtil {constructor() {this.storage = window.localStorage;}/*** 写入localStorage* @param key key* @param value value* @param expire 超时时间（以秒为单位）*/writeExpire(key, value, expire) {let tempObj = {};tempObj.key = key;tempObj.value = value;tempObj.expire = Date.now() + expire * 1000;this.storage[key] = JSON.stringify(tempObj);return tempObj;}/*** 读出localStorage*/readExpire(key) {let value = localStorage.getItem(key);if (!value || value === "null") {return null;}let valueObject = JSON.parse(value);let expire = valueObject["expire"];if (!expire) {return valueObject.value;}if (Date.now() >= expire) {this.remove(key);return null;}return valueObject.value}remove(key) {this.storage.removeItem(key);}
}export default LocalStorageUtil;
html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<script type="module">import LocalStorageUtil from "./LocalStorageUtil.js";let localStorageUtil = new LocalStorageUtil();localStorageUtil.writeExpire("key1", "value1", 2)console.log(localStorageUtil.readExpire("key1"));sleep(4000).then(() => {console.log(localStorageUtil.readExpire("key1"));})function sleep(time) {return new Promise((resolve) => setTimeout(resolve, time));}
</script>
</body>
</html>
