zig Tryit Editor

<!DOCTYPE html>
<html>
<style>
#mydiv {
  position: absolute;
  z-index: 9;
  background-color: #f1f1f1;
  text-align: center;
  border: 1px solid #d3d3d3;
}
#mydivheader {
  padding: 10px;
  cursor: move;
  z-index: 10;
  background-color: #2196F3;
  color: #fff;
}
</style>
<body>
<h1>Draggable DIV Element</h1>
<p>Click and hold the mouse button down while moving the DIV element</p>
<div id="mydiv">
  <div id="mydivheader">Click here to move</div>
  <p>Move</p>
  <p>this</p>
  <p>DIV</p>
</div>
<script>
  //Make the DIV element draggagle:
  dragElement(document.getElementById("mydiv"));
  function dragElement(elmnt) {
    var pos1 = 0, pos2 = 0, pos3 = 0, pos4 = 0;
    if (document.getElementById(elmnt.id + "header")) {
      /* if present, the header is where you move the DIV from:*/
      document.getElementById(elmnt.id + "header").onmousedown = dragMouseDown;
    } else {
      /* otherwise, move the DIV from anywhere inside the DIV:*/
      elmnt.onmousedown = dragMouseDown;
    }
    function dragMouseDown(e) {
      e = e || window.event;
      e.preventDefault();
      // get the mouse cursor position at startup:
      pos3 = e.clientX;
      pos4 = e.clientY;
      document.onmouseup = closeDragElement;
      // call a function whenever the cursor moves:
      document.onmousemove = elementDrag;
    }
    function elementDrag(e) {
      e = e || window.event;
      e.preventDefault();
      // calculate the new cursor position:
      pos1 = pos3 - e.clientX;
      pos2 = pos4 - e.clientY;
      pos3 = e.clientX;
      pos4 = e.clientY;
      // set the element's new position:
      elmnt.style.top = (elmnt.offsetTop - pos2) + "px";
      elmnt.style.left = (elmnt.offsetLeft - pos1) + "px";
    }
    function closeDragElement() {
      /* stop moving when mouse button is released:*/
      document.onmouseup = null;
      document.onmousemove = null;
    }
  }
</script>
</body>

</html>