Swap Draggables with Animation

http://stackoverflow.com/questions/13656611/how-to-swap-draggables-with-animation-using-jqueryui

by Ravindra Athreya

HTML

<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Swapping of tiles with Animation</title>
  <script src="http://cdnjs.cloudflare.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
  <script src="http://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.9.1/jquery-ui.min.js"></script>
  <style>
    .droppable {
      float: left;
      margin-left: 100px;
      width: 200px;
      height: 50px;
      border: 1px solid red;
      padding: 5px;
    }

    .draggable {
      width: 200px;
      height: 50px;
      background: green;
      text-align: center;
      line-height: 50px;
    }
    .ui-draggable-dragging {
      background: blue;
    }

    .hoverClass {
      border: 2px solid red;
    }
  </style>
</head>
<body>
  <div class='droppable'>
    <div class="draggable">Draggable 1</div>
  </div>
  
  <div class='droppable'>
    <div class="draggable">Draggable 2</div>
  </div>
    
     <div class='droppable'>
    <div class="draggable">Draggable 3</div>
  </div>
</body>
</html>

JavaScript

$(document).ready(function () {
      window.startPos = window.endPos = {};

      makeDraggable();

      $('.droppable').droppable({
        hoverClass: 'hoverClass',
        drop: function(event, ui) {
          var $from = $(ui.draggable),
              $fromParent = $from.parent(),
              $to = $(this).children(),
              $toParent = $(this);

          window.endPos = $to.offset();

          swap($from, $from.offset(), window.endPos, 200);
          swap($to, window.endPos, window.startPos, 1000, function() {
            $toParent.html($from.css({position: 'relative', left: '', top: '', 'z-index': ''}));
            $fromParent.html($to.css({position: 'relative', left: '', top: '', 'z-index': ''}));
            makeDraggable();
          });
        }
      });

      function makeDraggable() {
        $('.draggable').draggable({
          zIndex: 99999,
          revert: 'invalid',
          start: function(event, ui) {
            window.startPos = $(this).offset();
          }
        });
      }

      function swap($el, fromPos, toPos, duration, callback) {
        $el.css('position', 'absolute')
          .css(fromPos)
          .animate(toPos, duration, function() {
            if (callback) callback();
          });
      }
    });