lick'], (e) => {
        console.log('Change heading color!')
        e.target.style.color = `#${Math.floor(Math.random()*16777215).toString(16)}`
      });
      </script>

      <p>Open up console to see logs. View page source for example code</p>
      

      <button id="once">
        Run once via { once: true } option
      </button>
      <script>
      // Run once via once options
      const onceButton = document.querySelector('#once')
      addListener(onceButton, 'click', (e) => {
        console