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<h1>Hover to reorder</h1>

<div class="group">
  <div class="box">1</div>
  <div class="box">2</div>
  <div class="box">3</div>
  <div class="box">4</div>
</div>

var group = document.querySelector(".group");
var nodes = document.querySelectorAll(".box");
var total = nodes.length;
var ease  = Power1.easeInOut;
var boxes = [];

for (var i = 0; i < total; i++) {
  
  var node = nodes[i];
  
  // Initialize transforms on node
  TweenLite.set(node, { x: 0 });
   
  boxes[i] = {
    transform: node._gsTransform,
    x: node.offsetLeft,
    y: node.offsetTop,
    node    
  };
} 

group.addEventListener("mouseenter", layout);
group.addEventListener("mouseleave", layout);

function layout() {
  
  group.classList.toggle("reorder");  
  
  for (var i = 0; i < total; i++) {
    
    var box = boxes[i];
        
    var lastX = box.x;
    var lastY = box.y;
    
    box.x = box.node.offsetLeft;
    box.y = box.node.offsetTop;
    
    // Continue if box hasn't moved
    if (lastX === box.x && lastY === box.y) continue;
    
    // Reversed delta values taking into account current transforms
    var x = box.transform.x + lastX - box.x;
    var y = box.transform.y + lastY - box.y;  
    
    // Tween to 0 to remove the transforms
    TweenLite.fromTo(box.node, 0.5, { x, y }, { x: 0, y: 0, ease });    
  } 
}

<script src="//cdnjs.cloudflare.com/ajax/libs/gsap/1.18.0/TweenMax.min.js"></script>

body {
  color: #333;
  padding: 10px 24px;
}

h1 {
  font-weight: normal;
  font-size: 24px;
}

.group {
  width: 600px;
  height: 150px;
  padding: 4px;  
  background: #ddd;
  display: flex;
  flex-direction: row;  
}

.box {
  margin: 4px;
  padding: 8px;
  font-size: 18px;
  flex: 1;
  align-self: stretch;  
    
  &:nth-child(1) {
    background: rgba(63, 81, 181, 0.6);
  }
  
  &:nth-child(2) {
    background: rgba(103, 58, 183, 0.6);
  }
  
  &:nth-child(3) {
    background: rgba(33, 150, 243, 0.6);
  }
  
  &:nth-child(4) {
    background: rgba(0, 188, 212, 0.6);
  }
}

.group.reorder {
  
  .box:nth-child(1) {
    order: 2;
  }
  
  .box:nth-child(2) {
    order: 4;
  }
  
  .box:nth-child(3) {
    order: 1;
  }
  
  .box:nth-child(4) {
    order: 3;
  }
}