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Events as external clicks

If you want to track a few key external links that people could click on from your site to somewhere on the internet, you could do something like this: 
<a href="https://amazon.com/x" class="sponsored">Link to Amazon</a>
<a href="https://bestbuy.com/x" class="sponsored">Link to Bestbuy</a>
Where you’d add sponsored as a class to each link you wanted to collect data for. And then you’d add the following javascript to generate the events: 
<script>
window.addEventListener('load', (event) => {
  document.querySelectorAll('.sponsored').forEach(item => {
    item.addEventListener('click', event => {
      let url = new URL(item.getAttribute('href'));
      let domainParts = url.hostname.split('.');
      let domainName = domainParts.length > 1 ? domainParts[domainParts.length - 2] : domainParts[0];

      fathom.trackEvent(`Sponsor clicked: ${domainName}`);
    });
  });
});
</script>
For another example, if you wanted to track ALL external link clicks, you could use the following javascript: 
<script>
window.addEventListener('load', (event) => {
  document.querySelectorAll('a').forEach(item => {
    item.addEventListener('click', event => {
      let linkUrl = new URL(item.getAttribute('href'), window.location.href); // Using the second argument to handle relative URLs
      let currentHostname = window.location.hostname;

      if (linkUrl.hostname !== currentHostname) { // If the link's hostname is different from the current page's hostname
        let domainParts = linkUrl.hostname.split('.');
        let domainName = domainParts.length > 1 ? domainParts[domainParts.length - 2] : domainParts[0];

        fathom.trackEvent(`External link clicked: ${domainName}`);
      }
    });
  });
});
</script>