</button>
<button id="item-3" class="item three">3</button>
<button id="item-4" class="item four">4</button>
<p>Droppable</p>
<div id="zone-1" class="dropzone one"></div>
<div id="zone-2" class="dropzone two"></div>
<div id="zone-3" class="dropzone three"></div>
<div id="zone-4" class="dropzone four"></div>
<script>
    window.dropTarget = null
    window.ds = new DragSelect({
        selectables: document.querySelectorAll('.item'),
        dropZones: [
            { element: document.querySelector('#zone-1