title: Creating a simple Unique Booking ID function
body: <p>I need a special unique booking ID, which is easy for costumer to read-out over the phone.</p>
  
  <p>It should be 5 characters long, and only use these letters:</p>
  
  <pre><code>var letters = "ABCDEFGHJKMNPQRSTUXY";
  </code></pre>
  
  <p>I found this function on stackoverflow but is having a hard time to get it to take chars from my letters and limit itself to 5 chars. </p>
  
  <pre><code>var uniqueId = function() {
    return Math.random().toString(36).substr(2, 16);
  };
  </code></pre>
  
  <p>Any help would be appreciated :-)</p>