JSFiddle - React, Tailwind, and code Playground

HTML

<html>
    <body>
        <div id="pulse-element">Element</div>
    </body>
</html>

CSS

#pulse-element {
    padding: 5px;
    background-color: #f00;
}

JavaScript

$(document).ready(function() {
  $.fn.pulseEffect = function(delay, duration) {
    var $element, animateOptions;
    $element = $(this);
    if (!$element.is(":hover")) {
      animateOptions = {
        opacity: $element.css("opacity") === "1" ? .6 : 1
      };
      $element.animate(animateOptions, duration);
    }
    return setTimeout((function() {
      return $element.pulseEffect(delay, duration);
    }), delay + duration);
  };

  $("#pulse-element").pulseEffect(0, 1000);
});