AI solution for JavaScript Coding Question on BFE.dev
135. localStorage with expiration

class myLocalStorage {
  static setItem(key, value, ttl = null) {
    const now = Date.now();
    const item = {value: value, expiration: ttl ? now + ttl : null};
    localStorage.setItem(key, JSON.stringify(item));
  }

  static getItem(key) {
    const item = JSON.parse(localStorage.getItem(key));
    if (!item) {
      return null;
    }
    if (item.expiration && Date.now() > item.expiration) {
      localStorage.removeItem(key);
      return null;
    }
    return item.value;
  }
}

Explanation:

• setItem method accepts three parameters - key, value and ttl (time-to-live) which is optional and defaults to null.
• It creates an object item with value as the value parameter and expiration calculated based on the ttl parameter. If ttl is null, expiration is set to null.
• item object is then stored in localStorage with key as provided key parameter.
• getItem method accepts one parameter - key.
• It retrieves the item from localStorage with provided key and parses it into item object.
• If item is null, it returns null.
• If item has expiration and it has passed, it removes the item from localStorage and returns null.
• Otherwise, it returns the value of the item.