ajax验证用户名和找回密码参考

 // JavaScript Document
 function chkname(form){
     var user = form.user.value;
     if(user == ''){
         alert('请输入用户名');
         form.user.focus();
         return false;
     }else{
         var url = "foundpwd.php?user="+user;
         xmlhttp.open("GET",url,true);
         xmlhttp.onreadystatechange = function(){
         if(xmlhttp.readyState == 4){
                 var msg = xmlhttp.responseText;
                 if(msg == '0'){
                     alert('没有该用户，请重新查找!');
                     form.user.select();
                     return false;
                 }else{
                     document.getElementById('first').style.display = 'none';
                     document.getElementById('second').style.display = '';
                     document.getElementById('question').innerHTML = msg;
                 }
             }
         }
         xmlhttp.send(null);
     }
 }
 function chkanswer(form) {
     var user = document.getElementById('user').value;
     var answer = form.answer.value;
     if(answer == ''){
         alert('请输入提示问题');
         form.answer.focus();
         return false;
     }else{
         var url = "foundpwd.php?user="+user+"&answer="+answer;
         xmlhttp.open("GET",url,true);
         xmlhttp.onreadystatechange = function(){
             if(xmlhttp.readyState == 4){
                 var msg = xmlhttp.responseText;
                 if(msg == '0'){
                     alert('问题回答错误');
                     form.answer.select();
                     return false;
                 }else{
                     document.getElementById('second').style.display = 'none';
                     document.getElementById('third').style.display = '';
                 }
             }
         }
         xmlhttp.send(null);
     }
 }
 function chkpwd(form){
     var user = document.getElementById('user').value;
     var pwd1 = form.pwd1.value;
     var pwd2 = form.pwd2.value;
     if(pwd1 == ''){
         alert('请输入密码');
         form.pwd1.focus();
         return false;
     }
     if(pwd1.length < 6){
         alert('密码输入错误');
         form.pwd1.focus();
         return false;
     }
     if(pwd1 != pwd2){
         alert('两次密码不相等');
         form.pwd2.select();
         return false;
     }
     var url = "foundpwd.php?user="+user+"&password="+pwd1;
     xmlhttp.open("GET",url,true);
     xmlhttp.onreadystatechange = function(){
         if(xmlhttp.readyState == 4){
             var msg = xmlhttp.responseText;
             if(msg == '1'){
                 alert('密码修改成功，请重新登录');
                 window.close();
             }else{
                 alert(msg);
             }
         }
     }
     xmlhttp.send(null);
 }