Applying styling to a button contained within a translucent parent div on a CSS animation end. Applied a stronger background colour instead!

animationend.js

var newsArticles = document.querySelectorAll('.desktop .newspanel .news-article');
for (var i = 0; i < newsArticles.length; i++) {
  (function() {
    var element = newsArticles[i];
    element.addEventListener('animationend', function() {
      var style = window.getComputedStyle(element);
      var opacity = style.getPropertyValue('opacity');
      var selector = '.desktop .btn';
      var button = element.querySelector(selector);
      if (opacity == 0.9) {
        button.setAttribute('style', 'opacity: 1;background-color:rgba(0,0,0,1)');
      } else {
        button.setAttribute('style', 'opacity: 0');
      }
    });
  })();
}