Here's a simple example of a click-through ad script using JavaScript

<!-- HTML code for the ad -->
<a href="#" id="ad-link">
  <img src="/ad-image.jpg" alt="Advertisement">
</a>

<!-- JavaScript code for the ad -->
<script>
  // Get a reference to the ad link
  var adLink = document.getElementById('ad-link');

  // Add a click event listener to the ad link
  adLink.addEventListener('click', function(event) {
    // Prevent the default behavior of the link
    event.preventDefault();

    // Redirect the user to the ad destination URL
    window.location.href = 'https://www.example.com/ad-page';
  });
</script>

Replace the ad-image.jpg with the image file you want to use for the ad, and change the https://www.example.com/ad-page URL to the actual destination URL of your ad.

Note that some ad platforms have their own click tracking mechanisms, so you may need to use their provided code instead of the example above.