title: I want to delete specific object from localstorage
body: <p>Normally there is a function localstorage.remove(key). But i want to delete an index within a key.
  I am saving the object like that:</p>
  <pre><code>cart[idstr] = [qty, name];
  
  localStorage.setItem('cart', JSON.stringify(cart));
  </code></pre>
  <p>I want to delete a specific <code>cart[idstr]</code>
  Sample <code>console.log(cart)</code> is giving:</p>
  <pre><code>{pr22: Array(2), pr19: Array(2), pr21: Array(2)}
  </code></pre>
  <p>Suppose i want to delete pr19. What should i do?</p>