JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-3.4.0.js"></script>
<div>Reallylongword test</div>

CSS

div {
 
  max-width: 120px;
  width: auto;
  display: inline-block;

  border: 1px solid black;    
  padding: 0.2rem;
  
}

JavaScript

$.fn.textWidth = function(){
  var html_org = $(this).html();
  var html_calc = '<span>' + html_org + '</span>';
  $(this).html(html_calc);
  var width = $(this).find('span:first').width();
  $(this).html(html_org);
  return width;
};

var textWidth = $("div").textWidth();
$("div").width(textWidth);