阻止默认行为 阻止冒泡

var a = document.getElementById(‘a‘);
a.addEventListener(‘click‘,function(e){
    e.preventDefault();
},false);

function preventDefault(event){
    var event = $$.getEvent(event);
    if(event.preventDefault){
        event.preventDefault();
    }else{
        event.returnValue = false; //微软
    }
}

$$(‘div2‘).addEventListener(‘click‘,function(event){
    event.stopPropagation();
},false)

function stopPropagation(event){
    var event = $$.getEvent(event);
    if(event.stopPropagation){
        event.stopPropagation();
    }else{
        event.cancelBubble = true;
    }
}