window.onload = function() {    //冒泡事件就是有内到外，由下至上如冒泡般触发的顺序    document.onclick = function(){        alert(‘document‘);    };    document.documentElement.onclick = function(){        alert(‘HTML‘);    };    document.body.onclick = function(){        alert(‘body‘);    };    document.getElementById(‘box‘).onclick = function(){        alert(‘div‘);    };    document.getElementById(‘input‘).onclick = function(evt){        //阻止冒泡需要stopPropagation()方法        var e = evt || window.event;        alert(‘input‘);        if(e.stopPropagation){            e.stopPropagation();        }else {            e.cancelBubble = true;    //IE兼容        }            };}