var $input = document.getElementsByTagName("input")[0];
var $div = document.getElementsByTagName("div")[0];
var $body = document.getElementsByTagName("body")[0];

$input.onclick = function(e){
 this.style.border = "5px solid red"
 var e = e || window.e;
 alert("red")
}
 $div.onclick = function(e){
 this.style.border = "5px solid green"
 alert("green")
}
$body.onclick = function(e){
 this.style.border = "5px solid yellow"
 alert("yellow")
}

<div>
 <input type="button" value="测试事件冒泡" />
</div> 依次弹出”red“,"green","yellow"。

$input.onclick = function(e){
 this.style.border = "5px solid red"
 var e = e || window.e;
 alert("red")
 e.stopPropagation();
}

$input.addEventListener("click", function(){
 this.style.border = "5px solid red";
 alert("red")
}, true)
$div.addEventListener("click", function(){
 this.style.border = "5px solid green";
 alert("green")
}, true)
$body.addEventListener("click", function(){
 this.style.border = "5px solid yellow";
 alert("yellow")
}, true)

var $a = document.getElementsByTagName("a")[0];
$a.onclick = function(e){
 alert("跳转动作被我阻止了")
 e.preventDefault();
 //return false;//也可以
}

<a href="http://keleyi.com">柯乐义</a>默认事件没有了。