function checkdata(){
var username=document.getElementById("username")
var userEmpt=document.getElementById("userEmpt")
if (username.value==""){
userEmpt.innerHTML="请输入用户名"
username.focus();
return false;
}
else{
userEmpt.innerHTML=""
}
var pwd=document.getElementById("pwd")
var pwdEmpt=document.getElementById("pwdEmpt")
if (pwd.value==""){
pwdEmpt.innerHTML="请输入密码"
pwd.focus();
return false;
}
else{
pwdEmpt.innerHTML=""
}
return true;
}