jQuery addClass example

Change class name on click in jQuery

HTML

<div id="1" class="allow">A div</div>

JavaScript

setTimeout(function() {
$("#1").addClass('passed');
}, 3000);

var observer = new MutationObserver(function(mutations) {
  mutations.forEach(function(mutation) {
    if (mutation.attributeName === "class") {
      var attributeValue = $(mutation.target).prop(mutation.attributeName);
      var allElementClasses = attributeValue.split(' ')
      alert("class was added: " + allElementClasses[allElementClasses.length - 1])
      if(allElementClasses[allElementClasses.length - 1] === "passed"){
      //do something
      }
    }
  });
});

observer.observe(document.getElementById('1'), {
  attributes: true
});