Code for dynamically adding events (binding events) in JS

var tb = ("tab1");
if(){ // Mozilla, Netscape, Firefox
td_value.addEventListener('click', alert('11'), false);
td_value.addEventListener('click', alert('12'), false);
} else { // IE
td_value.attachEvent('onclick', function(){alert('21');});
td_value.attachEvent('onclick', function(){alert('2'2);});
}