JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
  <li data-ratio="4/3">4:3</li>
  <li data-ratio="1/2">1:2</li>
  <li data-ratio="16/9">16/9</li>
</ul>

JavaScript

$('li').on('click', function(event) {
  var values = $(this).attr('data-ratio').split('/');
  var ratio = parseInt(values[0], 10) / parseInt(values[1], 10);
  alert(ratio);
});