title: Add/Remove item from array - javascript
body: <p>I was wondering how I can add/remove item to array depending on if it's already in there.</p>
  
  <p>Basically, I have a list of items and every item has their own ID, I want to add it or remove it depending on if it's already in the basket array and indicate (with css) if it's already in there.</p>
  
  <p>Thanks in advance.</p>