feat: add ExpireStorage class

Author: chachaxw

js/expire_storage.js

@@ -0,0 +1,54 @@
+/*
+ * @Author: Chacha
+ * @Date: 2022-05-29 11:19:24
+ * @Last Modified by: Chacha
+ * @Last Modified time: 2022-05-29 13:18:34
+ */
+
+/**
+ * Expire storage，支持过期时间的 localStorage
+ */
+
+class ExpireStorage {
+    prefix = "Chacha";
+
+    tag = "|Chacha|";
+
+    defaultTime = Date.now() + 24 * 60 * 60 * 31 * 1000; // 默认时长1个月
+
+    constructor(prefix, tag) {
+        this.prefix = prefix;
+        this.tag = tag;
+    }
+
+    setItem(key, value, time) {
+        key = `${this.prefix}${key}`;
+        time = time ? new Date(time).getTime() : this.defaultTime;
+
+        // 构造一个形如 1646094676134|Chacha|"Hello World" 结构的字符串
+        window.localStorage.setItem(
+            key,
+            `${time}${this.tag}${JSON.stringify(value)}`
+        );
+    }
+
+    getItem(key) {
+        key = `${this.prefix}${key}`;
+        let value = window.localStorage.getItem(key);
+
+        if (value) {
+            let index = value.indexOf(this.tag);
+            let time = +value.slice(0, index);
+
+            // 判断时间是否已过期
+            if (time > Date.now()) {
+                value = JSON.parse(value.slice(index + this.tag.length));
+            } else {
+                value = null;
+                window.localStorage.removeItem(key);
+            }
+        }
+
+        return value;
+    }
+}