Where to run JavaScript
<!DOCTYPE html>
<html>
  <head>
    <title>My first JavaScript</title>
  </head>
  <body>
    <h1>My first JavaScript</h1>
    <p>Click the button to display the date and time.</p>
    <button onclick="document.getElementById('demo').innerHTML = Date()">
      The time is?
    </button>
    <p id="demo"></p>
  </body>
</html>