<pre class="shiki github-dark shaku"><code>/** * CustomLocalStorage - A wrapper for localStorage that includes support for setting items with an expiration time. * * Requirements: * 1. Save values under keys, similar to regular localStorage. * 2.Allow an optional expiration time (in milliseconds) when storing items. * - If an expiration time is set, the item should automatically be removed once it expires. * 3. Methods to Implement: * - setItem(key, value, maxAge)**: Stores `value` under `key` in localStorage. * - If `maxAge` is provided, calculate an `expiryTime` (current time + maxAge) for automatic removal. * - getItem(key): Retrieves the value of `key` if it exists and hasn’t expired; if expired, it should return `null`. * - removeItem(key): Removes the specified item from storage. * - clear(): Clears all items in storage. * * Example: * - Setting `key="session"` with `value="active"` and `maxAge=5000` means the session will expire after 5 seconds. * - After 5 seconds, calling `getItem("session")` should return `null` since it has expired. */// Define the object with a proper structure under `window.myLocalStorage`window.myLocalStorage = { // Set an item in storage with an optional expiration time /** * @param {string} key - The key to store the value under. * @param {any} value - The value to store. * @param {number} [maxAge] - Optional. Time in milliseconds after which the item should expire. */ setItem: function(key, value, maxAge) { // If maxAge = 0, delete it instantly, so no data is stored if (maxAge === 0) { this.removeItem(key); return; } // Calculate expiry time if maxAge is provided const data = maxAge ? JSON.stringify({ value, expiryTime: Date.now() + maxAge }) : JSON.stringify({ value }); // Store data in localStorage under the provided key localStorage.setItem(key, data); }, // Retrieve an item from storage and handle expiration /** * @param {string} key - The key of the item to retrieve. * @returns {any|null} - The value if it exists and hasn't expired; otherwise, `null`. */ getItem: function(key) { // Retrieve the stored item from localStorage const item = JSON.parse(localStorage.getItem(key)); // If the item doesn't exist, return null if (!item) return null; // If the item has an expiryTime and it's passed, remove the item and return null if (item.expiryTime &amp;&amp; item.expiryTime &lt; Date.now()) { this.removeItem(key); // Remove expired item return null; } // Return the value if it hasn't expired return item.value; }, // Remove an item from storage /** * @param {string} key - The key of the item to remove. */ removeItem: function(key) { localStorage.removeItem(key); }, // Clear all items from storage clear: function() { localStorage.clear(); }};// Example usage and testing:// Test 1: Setting and getting an item without expirationwindow.myLocalStorage.setItem("name", "Alice");console.log(window.myLocalStorage.getItem("name")); // Should print: "Alice"// Test 2: Setting an item with a 3-second expirationwindow.myLocalStorage.setItem("session", "active", 3000);console.log(window.myLocalStorage.getItem("session")); // Should print: "active"// Wait for 4 seconds to check if the item has expiredsetTimeout(() =&gt; { console.log(window.myLocalStorage.getItem("session")); // Should print: null (expired)}, 4000);// Test 3: Removing an itemwindow.myLocalStorage.setItem("temp", "temporary");window.myLocalStorage.removeItem("temp");console.log(window.myLocalStorage.getItem("temp")); // Should print: null (item was removed)// Test 4: Clearing all itemswindow.myLocalStorage.setItem("user", "Bob");window.myLocalStorage.setItem("token", "abc123");window.myLocalStorage.clear();console.log(window.myLocalStorage.getItem("user")); // Should print: null (storage is cleared)console.log(window.myLocalStorage.getItem("token")); // Should print: null (storage is cleared)//</code></pre>

with good explanation by krishna saini

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localStorage is a simple and handy client-side storage, but you should avoid using it because it is synchronous. Also Safari's ITP actually deletes cl…