<!--
Forum question answer only:

https://www.sitepoint.com/community/t/drag-n-drop-multiple-divs/407620

-->

<h1>Draggable DIV Element</h1>
<p>Click and hold the mouse button down while moving the DIV element</p>
<div class="mydiv div1">
  <div class="mydivheader">Click here to move</div>
  <p>Move</p>
  <p>this</p>
  <p>DIV</p>
</div>

<div class="mydiv div2">
  <div class="mydivheader">Click here to move</div>
  <p>Move</p>
  <p>this</p>
  <p>DIV</p>
</div>

<div class="mydiv div3">
  <div class="mydivheader">Click here to move</div>
  <p>Move</p>
  <p>this</p>
  <p>DIV</p>
</div>

<div class="mydiv div4">
  <p>Move</p>
  <p>this</p>
  <p>DIV</p>
</div>

.mydiv {
  position: absolute;
  display: table;
  min-width: 150px;
  z-index: 9;
  background-color: #f1f1f1;
  text-align: center;
  border: 1px solid #d3d3d3;
  cursor: move;
}

.mydivheader {
  padding: 10px;
  cursor: move;
  z-index: 10;
  background-color: #2196f3;
  color: #fff;
}
.div2 {
  left: 200px;
}
.div3 {
  left: 400px;
}
.div4 {
  left: 600px;
}

const els = document.querySelectorAll(".mydiv");
els.forEach((name) => {
  dragElement(name);
});

function dragElement(elmnt) {
  var pos1 = 0,
    pos2 = 0,
    pos3 = 0,
    pos4 = 0;
  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;
  }
}