title: Make Select2 fetch data only once
body: <p>I'm using Select2 builtin AJAX to load a tiny list of items. Select2 loads the entire list on first selection (good) but reloads the JSON feed every time the user tries to change his selection or type to filter items (and that means a new AJAX request for each typed letter!).</p>
  
  <p>At <a href="https://select2.github.io/options.html#a-request-is-being-triggered-on-every-key-stroke-can-i-delay-th" rel="nofollow noreferrer">A request is being triggered on every key stroke, can I delay this?</a> we can read:</p>
  
  <blockquote>
    <p>By default, Select2 will trigger a new AJAX request whenever the user
    changes their search term. You can set a time limit for debouncing
    requests using the <code>ajax.delay</code> option.</p>
  
  <pre><code>$('select').select2({
      ajax: {
          url: '/example/api',
          delay: 250
      }
  });
  </code></pre>
    
    <p>This will tell Select2 to wait 250 milliseconds before sending the request out to your API.</p>
  </blockquote>
  
  <p>... but it doesn't. Seriously. I've also tried the undocumented <code>minimumInputLength</code> property shown in examples but it doesn't seem to do anything.</p>
  
  <p>Is it even possible to make Select2 fetch data only once?</p>