如图：
[I]screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onclick="if(!this.resized) {return true;} else {window.open('http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4108996');}" alt="" src="http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4108996" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" border=0>
红色部分就是一会要调用的js函数了，当我们选定一个文本框后就会开始调用，现在我们看上面那个页面包含的ajaxreg.js文件的代码，里面就是包含了ajax框架和一些判断函数。
var http_request=false;
function send_request(url){//初始化，指定处理函数，发送请求的函数
http_request=false;
//开始初始化XMLHttpRequest对象
if(window.XMLHttpRequest){//Mozilla浏览器
http_request=new XMLHttpRequest();
if(http_request.overrideMimeType){//设置MIME类别
http_request.overrideMimeType("text/xml");
}
}
else if(window.ActiveXObject){//IE浏览器
try{
http_request=new ActiveXObject("Msxml2.XMLHttp");
}catch(e){
try{
http_request=new ActiveXobject("Microsoft.XMLHttp");
}catch(e){}
}
}
if(!http_request){//异常，创建对象实例失败
window.alert("创建XMLHttp对象失败！");
return false;
}
http_request.onreadystatechange=processrequest;
//确定发送请求方式，URL，及是否同步执行下段代码
http_request.open("GET",url,true);
http_request.send(null);
}
//处理返回信息的函数
function processrequest(){
if(http_request.readyState==4){//判断对象状态
if(http_request.status==200){//信息已成功返回，开始处理信息
document.getElementById(reobj).innerHTML=http_request.responseText;
}
else{//页面不正常
alert("您所请求的页面不正常！");
}
}
}
function usercheck(obj){
var f=document.reg;
var username=f.username.value;
if(username==""){
document.getElementById(obj).innerHTML="
用户名不能为空！
";
f.username.focus();
return false;
}
else{
document.getElementById(obj).innerHTML="正在读取数据...";
send_request('checkuserreg.php?username='+username);
reobj=obj;
}
}
function pwdcheck(obj){
var f=document.reg;
var pwd=f.userpwd.value;
if(pwd==""){
document.getElementById(obj).innerHTML="
用户密码不能为空！
";
f.userpwd.focus();
return false;
}
else if(f.userpwd.value.length
不难看出，数据是通过异步传输到checkuserreg.php接着回送回信息显示出来来达到实时检测用户名的目的，至于密码，只作了长度的实时判断，有兴趣的朋友可以扩充功能。来看下checkuserreg.php到底都做了什么：
mysql($dbhost,$dbuser,$dbpassword,$dbname);//调用连接参数函数
$db->createcon();//调用创建连接函数
//-----------------------------------------------------------------------------------
$querysql="select username from cr_userinfo where username='$username'";//查询会员名
$result=$db->query($querysql);
$rows=$db->loop_query($result);
//若会员名已注册
//-----------------------------------------------------------------------------------
if($rows){
echo"
此会员名已被注册，请更换会员名！
";
}
//会员名未注册则显示
//-----------------------------------------------------------------------------------
else{
echo"
此会员名可以注册！
";
}
if($action==reg){
$addsql="insert into cr_userinfo
values(0,'$username','$userpwd','$time',50,1,'$userquestion','$useranswer')";
$db->query($addsql);
echo"
[img][/img]
恭喜您，注册成功！请点击[url=]这里[/url]登陆！";
}
$db->close();//关闭数据库连接
?>
注释写的还算详细，大家应该都能看懂，再看信息合法后我们提交注册信息实现无刷新注册的PHP代码,senduserinfo.php：
mysql($dbhost,$dbuser,$dbpassword,$dbname);//调用连接参数函数
$db->createcon();//调用创建连接函数
//-----------------------------------------------------------------------------------
//开始插入数据
//-----------------------------------------------------------------------------------
$addsql="insert into cr_userinfo values(0,'$username','$userpwd','$time',50,1,'$userquestion','$useranswer')";
$db->query($addsql);
echo"
[img][/img]
恭喜您，注册成功！请点击[url=]这里[/url]登录！";
$db->close();//关闭数据库连接
?>
OK！！大功告成，来看看效果图：
1.
[I]screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onclick="if(!this.resized) {return true;} else {window.open('http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4109258');}" alt="" src="http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4109258" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" border=0>
2.
[I]screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onclick="if(!this.resized) {return true;} else {window.open('http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4109286');}" alt="" src="http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4109286" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" border=0>
3.
[I]screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onclick="if(!this.resized) {return true;} else {window.open('http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4109299');}" alt="" src="http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4109299" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" border=0>
4.
[I]screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onclick="if(!this.resized) {return true;} else {window.open('http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4109333');}" alt="" src="http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4109333" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" border=0>
5.
[I]screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onclick="if(!this.resized) {return true;} else {window.open('http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4109336');}" alt="" src="http://leehui1983.bokee.com/photo/view.fcgi?mode=3&id=4109336" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" border=0>
怎么样？还不错吧，贴了这么多累死了，希望大家喜欢～～～～