您好，当js加入ajax代码后就不能运行了，alert也不可以用，这是什么原因呢？

Question

代码后就不可以用了。求解释啊！昨天调试了一天了，今天又弄了好久，实在是没办法了。代码如下：
// JavaScript Document
var xmlHttp;
function sendmsg(s)
{
var messag=""
if (s=="2")
{
message=document.getElementById("message").innerHTML;
if(messag==""){
alert("请输入内容");
return
}
}
}
function sendmg(s)
{
var message=""
if (s=="2")
{
message=document.getElementById("message").innerHTML;
if(message==""){
alert("请输入内容");
return
}
}
xmlHttp=GetXmlHttpObject()
if (xmlHttp==null)
{
alert ("您好！您的浏览器不支持ajax技术，请升级或使用较新版本的ie浏览器。");
return
} 
var url="qingtan_ajax.php"
url=url+"?t="+Math.random()
xmlHttp.open("POST",url,true); 
xmlHttp.onreadystatechange=stateChanged 
xmlHttpRequest.setRequestHeder("Content-Type","application/x-www-form-urlencoded;charset=gb2312");
xmlHttpRequest.send("author=阿墨&message="+message+"&touser=默默"); 
}
function stateChanged() 
{ 
if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
{ 
if (xmlHttp.responseText==""){
alert("nothing returned"); 
}
if(xmlHttp.responseText<>"norefresh"){
document.getElementById("Layer6").innerHTML=xmlHttp.responseText 
}
} 
}
function GetXmlHttpObject()
{
var xmlHttp=null;
try
{
// Firefox, Opera 8.0+, Safari
xmlHttp=new XMLHttpRequest();
}
catch (e)
{
// Internet Explorer
try
{
xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e)
{
xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
}
}
return xmlHttp;
}

Answer 1

这边写了个实例，源代码如下<script>function loadXMLDoc(){var xmlhttp;if (window.XMLHttpRequest){// code for IE7+, Firefox, Chrome, Opera, Safarixmlhttp=new XMLHttpRequest();}else{// code for IE6, IE5xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");}xmlhttp.onreadystatechange=function(){if (xmlhttp.readyState==4 && xmlhttp.status==200){document.getElementById("msgbox").innerHTML+=xmlhttp.responseText;}}xmlhttp.open("post","getwords.asp" ,true);xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");xmlhttp.send("yourwords="+document.getElementById("yourwords").value);return false;}</script><textarea name="content" cols="30" rows="10" id=yourwords></textarea><input type=button onclick="loadXMLDoc()" value="提交"></form><hr><div id=msgbox></div>服务器响应源代码：getwords.asp<%response.write Request.form("yourwords")&"<br>"%>&nbsp;

Answer 2

message=document.getElementById("message").innerHTML;这里是不是少了点东西啊message=document.getElementById("message")[0].innerHTML;你试试