<button id="menu">Menu (click me)</button>

<script>
  menu.onclick = function() {
    alert(1);

    menu.dispatchEvent(new CustomEvent("menu-open", {
      bubbles: true
    }));

    alert(2);
  };

  //  يفتعل بين 1 و 2
  document.addEventListener('menu-open', () => alert('nested'));
</script>