TryIt Editor v2.0 - javascript addEventListener

Source Code: (back to article)

<!DOCTYPE html>
<html>
  <head>
    <title>Title of the document</title>
    <style type="text/css">
      body {
        text-align: center;
      }
      .oldClassName {
        background-color: green;
      }
      .newClassName {
        background-color: blue;
      }
      .pId {
        margin-top: 30px;
      }
      #buttonId {
        padding: 15px;
      }
    </style>
  </head>
  <body>
    <h2>Chenge class name</h2>
    <button class="oldClassName" id="buttonId">Click on Button</button>
    <br>
    <p id="pId">Old class name: oldClassName </p>
    <script type="text/javascript">
      function changeClass() {
        document.getElementById('buttonId').className = "newClassName";
        let button_class = document.getElementById('buttonId').className;
        document.getElementById('pId').innerHTML = "New class name: " + button_class;
      }
      window.onload = function() {
        document.getElementById("buttonId").addEventListener('click', changeClass);
      }
    </script>
  </body>
</html>