Let's define what happens when visitors click on the Generate a username button.

Code generate() between the quotes of the onclick attribute.

<html>
<body>
  <p id="name">JohnnyG</p>
  <p id="age">25</p>
  <button onclick="generate()">Generate a username</button>
  <p id="username"></p>
  <script src="script.js"></script>
</body>
</html>
]]>

Make sure to code generate().