I wrote simple code for it without any third-party library. This code is only for a horizontal splitter (vertical is the same).
function onload()
{
dragElement( document.getElementById("separator"), "H" );
}
// This function is used for dragging and moving
function dragElement( element, direction, handler )
{
// Two variables for tracking positions of the cursor
const drag = { x : 0, y : 0 };
const delta = { x : 0, y : 0 };
/* If present, the handler is where you move the DIV from
otherwise, move the DIV from anywhere inside the DIV */
handler ? ( handler.onmousedown = dragMouseDown ): ( element.onmousedown = dragMouseDown );
// A function that will be called whenever the down event of the mouse is raised
function dragMouseDown( e )
{
drag.x = e.clientX;
drag.y = e.clientY;
document.onmousemove = onMouseMove;
document.onmouseup = () => { document.onmousemove = document.onmouseup = null; }
}
// A function that will be called whenever the up event of the mouse is raised
function onMouseMove( e )
{
const currentX = e.clientX;
const currentY = e.clientY;
delta.x = currentX - drag.x;
delta.y = currentY - drag.y;
const offsetLeft = element.offsetLeft;
const offsetTop = element.offsetTop;
const first = document.getElementById("first");
const second = document.getElementById("second");
let firstWidth = first.offsetWidth;
let secondWidth = second.offsetWidth;
if (direction === "H" ) // Horizontal
{
element.style.left = offsetLeft + delta.x + "px";
firstWidth += delta.x;
secondWidth -= delta.x;
}
drag.x = currentX;
drag.y = currentY;
first.style.width = firstWidth + "px";
second.style.width = secondWidth + "px";
}
}.splitter {
width: 500px;
height: 100px;
display: flex;
}
#separator {
cursor: col-resize;
background: url(https://raw.githubusercontent.com/RickStrahl/jquery-resizable/master/assets/vsizegrip.png) center center no-repeat #535353;
width: 10px;
height: 100px;
min-width: 10px;
}
#first {
background-color: green;
width: 100px;
height: 100px;
min-width: 10px;
}
#second {
background-color: red;
width: 390px;
height: 100px;
min-width: 10px;
}<html>
<head>
<link rel="stylesheet" href="T10-Splitter.css">
<script src="T10-Splitter.js"></script>
</head>
<body onload="onload()">
<div class="splitter">
<div id="first"></div>
<div id="separator"></div>
<div id="second"></div>
</div>
</body>
</html>