Improved caching for integrity checks on client side.

frontend/utils/cache.js

@@ -0,0 +1,88 @@
+/**
+ * Cache class
+ *
+ * @class
+ * @param {string} engine - The engine to use for caching. Either 'session' or 'local'.
+ * @throws {Error} If the engine is not supported.
+ */
+class Cache {
+    supportedEngines = ['session', 'local']
+
+    constructor(engine = 'session') {
+        if (!this.supportedEngines.includes(engine)) {
+            throw new Error(`Engine '${engine}' not supported.`)
+        }
+
+        if ('session' === engine) {
+            this.storage = window.sessionStorage
+        } else {
+            this.storage = window.localStorage
+        }
+    }
+
+    /**
+     * Set a value in the cache
+     *
+     * @param key {string}
+     * @param value {*}
+     * @param ttl {number|null} - Time to live in milliseconds. If null, the value will not expire.
+     */
+    set(key, value, ttl = null) {
+        this.storage.setItem(key, JSON.stringify({value, ttl, time: Date.now()}))
+    }
+
+    /**
+     * Get a value from the cache
+     *
+     * @param key {string}
+     * @returns {any}
+     */
+    get(key) {
+        const item = this.storage.getItem(key)
+        if (null === item) {
+            return null
+        }
+
+        try {
+            const {value, ttl, time} = JSON.parse(item)
+            if (null !== ttl && Date.now() - time > ttl) {
+                this.remove(key)
+                return null
+            }
+            return value
+        } catch (e) {
+            return item
+        }
+    }
+
+    /**
+     * Remove a value from the cache
+     *
+     * @param key {string}
+     */
+    remove(key) {
+        this.storage.removeItem(key)
+    }
+
+    /**
+     * Clear the cache
+     */
+    clear() {
+        this.storage.clear()
+    }
+
+    /**
+     * Check if a key is in the cache
+     *
+     * @param key {string}
+     * @returns {boolean}
+     */
+    has(key) {
+        return null !== this.get(key)
+    }
+}
+
+const useSessionCache = () => new Cache('session')
+const useLocalCache = () => new Cache('local')
+
+export {useSessionCache, useLocalCache, Cache}