JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

JavaScript

var iframe = document.createElement('iframe');
var html = '<body><div id="cadrage" style="color:black">Test</div></body>';
iframe.src = 'data:text/html;charset=utf-8,' + encodeURI(html);
document.body.appendChild(iframe);


$('iframe').load( function() {
      if( $('iframe').contents().find("#cadrage").css('color') == "rgb(0, 0, 0)" ) {
        alert('It equal');
      } else {
        alert('It did not equal');
      }
});