JSFiddle - React, Tailwind, and code Playground

HTML

<div id="resizable"> Hi this is resiable div </div>

<br><br>

<span> Width: </span>
<input type="text" id="wt" value="300px"></input>

CSS

div
{
  top: 100px;
  bottom: 120px;
  width:100%;
  Height:100%;
border:2px solid blue;
padding:10px 40px; 
width:300px;
resize:both;
}

JavaScript

var input = $('input'), div = $('#resizable');
function calculate(){
    input.val(div.width()+"px");
}
setInterval(calculate,500);