就是这几句看不懂,请指教
if (window.XMLHttpRequest)
{
req = new XMLHttpRequest();
} else if (window.ActiveXObject) {
req = new ActiveXObject("Microsoft.XMLHTTP");
}
document.getElementById( "content" ).innerHTML = ".......正在验证,请稍候.........";
req.onreadystatechange = processChech;
req.open( "get", "./checkusername.jsp?username="+username, false );
req.send();
}全部代码如下:
function checkUsername()
{
var username = form.username.value;
if( username == "" || username == null )
{
alert( "请先填写用户名!" );
return;
}
switch( isUsername( username ) )
{
case 0: break;
case 1:
{
changeUsernamePrompt( "·您选择的用户名‘"+username+"’格式不正确,用户名不能以数字开头" );
return;
}
case 2:
{
changeUsernamePrompt( "·您选择的用户名‘"+username+"’字符长度有误,合法长度为5-20个字符" );
return;
}
case 3:
{
changeUsernamePrompt( "·您选择的用户名‘"+username+"’含有非法字符,用户名只能包含_,英文字母,数字" );
return;
}
case 4:
{
changeUsernamePrompt( "·您选择的用户名‘"+username+"’格式不正确,用户名只能包含_,英文字母,数字" );
return;
}
}
if (window.XMLHttpRequest)
{
req = new XMLHttpRequest();
} else if (window.ActiveXObject) {
req = new ActiveXObject("Microsoft.XMLHTTP");
}
document.getElementById( "content" ).innerHTML = ".......正在验证,请稍候.........";
req.onreadystatechange = processChech;
req.open( "get", "./checkusername.jsp?username="+username, false );
req.send();
}
if (window.XMLHttpRequest)
{
req = new XMLHttpRequest();
} else if (window.ActiveXObject) {
req = new ActiveXObject("Microsoft.XMLHTTP");
}
document.getElementById( "content" ).innerHTML = ".......正在验证,请稍候.........";
req.onreadystatechange = processChech;
req.open( "get", "./checkusername.jsp?username="+username, false );
req.send();
}全部代码如下:
function checkUsername()
{
var username = form.username.value;
if( username == "" || username == null )
{
alert( "请先填写用户名!" );
return;
}
switch( isUsername( username ) )
{
case 0: break;
case 1:
{
changeUsernamePrompt( "·您选择的用户名‘"+username+"’格式不正确,用户名不能以数字开头" );
return;
}
case 2:
{
changeUsernamePrompt( "·您选择的用户名‘"+username+"’字符长度有误,合法长度为5-20个字符" );
return;
}
case 3:
{
changeUsernamePrompt( "·您选择的用户名‘"+username+"’含有非法字符,用户名只能包含_,英文字母,数字" );
return;
}
case 4:
{
changeUsernamePrompt( "·您选择的用户名‘"+username+"’格式不正确,用户名只能包含_,英文字母,数字" );
return;
}
}
if (window.XMLHttpRequest)
{
req = new XMLHttpRequest();
} else if (window.ActiveXObject) {
req = new ActiveXObject("Microsoft.XMLHTTP");
}
document.getElementById( "content" ).innerHTML = ".......正在验证,请稍候.........";
req.onreadystatechange = processChech;
req.open( "get", "./checkusername.jsp?username="+username, false );
req.send();
}
if (window.XMLHttpRequest)
{
req = new XMLHttpRequest();
}
else if (window.ActiveXObject)
{
req = new ActiveXObject("Microsoft.XMLHTTP");
}
//向页面某个对象写内容,此处是写提示信息,表示正在验证
document.getElementById( "content" ).innerHTML = ".......正在验证,请稍候.........";
req.onreadystatechange = processChech;
//开始向验证页面发送信息,把你所选择的用户名发送过去
req.open( "get", "./checkusername.jsp?username="+username, false );
req.send();这是一个应用xmlhttp实现无刷新验证用户的代码.其中,在checkusername.jsp页面,即有根据传递的用户名,验证用户是否正确的代码.你可自行查看.