How to capture click event in prototype

I want to prevent default link click behavi开发者_C百科or. I want that it should not redirect to that link but just show the link in alert box. I have tried this here.

document.on('click', 'a.AjaxLink', function(event, element) {
    alert(element.href);
    return false;
});

this should work

document.on('click', 'a.AjaxLink', function(event, element) {
    event.stop();
    alert(element.href);
});