javascript 解决表单仍然提交即使监听处理函数返回false

<form action="http://www.jb51.net" id="form"> 
<input type="text" /> 
<input type="submit" /> 
</form> 
<script> 
var code = function () { 
return false; 
}; 
var element = window.document.getElementById("form"); 
if (element.addEventListener) { 
element.addEventListener("submit", code, false); 
} 
</script>

<form action="http://www.jb51.net" id="form"> 
<input type="text" /> 
<input type="submit" id="btnSubmit" name="btnSubmit" value="Submit" /> 
</form> 
<script> 
var code = function (eventObject) { 
if (eventObject.preventDefault) { 
eventObject.preventDefault(); 
} else if (window.event) /* for ie */ { 
window.event.returnValue = false; 
} 
return true; 
}; 
window.onload = function(){ 
var element = window.document.getElementById("form"); 
if (element.addEventListener) { 
element.addEventListener("submit", code, false); 
} else if (element.attachEvent) { 
element.attachEvent("onsubmit", code); 
} 
} 
</script>