JSFiddle - React, Tailwind, and code Playground

HTML

<div id="before"></div>
    <div id="after"></div>

CSS

div { width: 400px; height: 100px; background: red;   }
#after {
  display: none;
  -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";
  filter: alpha(Opacity=50);
}

JavaScript

$('#before').html('Before fadeIn the filter css property on #after is: ' + $('#after').css('filter'));
$('#after').fadeIn('fast', function() {
    $('#after').html('After fadeIn the filter css property on #after is: ' + $('#after').css('filter'));
});