check.js如下：
<script>
function check(){
}
function docheck(){
var loginname = document.getElementById("username").value;
if(loginname==""){
document.getElementById("div").style.display="none";
return false;
}else{
document.getElementById("div").innerHTML=" <img src = '10.jpg'>";
document.getElementById("div").style.display="block";
send_request();
}
}
function send_request(){
var loginname = document.getElementById("username").value;
url = "login.jsp?username="+loginname;
http_request=false;
if(window.XMLHttpRequest){
http_request = new XMLHttpRequest();
if(http_request.ovverideMimeType){
http_request.ovverideMimeType('text/xml');
}
}else if{
try{
http_request = new ActiveXObject("Msxml2.XHMHTTP");
}catch(e){
try{
http_request = new ActiveXBbject("Miscrosoft.XMLHTTP");
}catch(e){}
}
}
if(!http_rquest){
return false;
&n
