var parent = document.getElementById('parent'),
    child  = document.getElementById('child'),
    op     = document.getElementById('op'),
    op2    = document.getElementById('op2');

parent.addEventListener('click', function () {
  op.innerHTML += '<p>click registered</p>';
}, false);

function stopEvent (e) {
  e.stopPropagation();
  op2.innerHTML += '<p>propagation stopped</p>';
}

child.addEventListener('click', stopEvent, false);