JQuery calls webservice to implement email verification (checking whether it is available)_jquery

Copy code The code is as follows:

SinaWeiBo.WebService1.cunzai($(this).val(), a, b)
{
function a(result) {
if (result == "The email already exists, please re-enter") {
$('#txtusername').val('');
$('#txtusername').focus();
$('#mailyz').text(result);
}
else { $('#emailz').text('can be used'); }
}
function b() {
$('#emailz').text( 'No return value');
}
}

webservice:

Copy code The code is as follows:

public string cunzai(string txtusername)
{
//Determine whether the mailbox exists
try
{
SinaWeiBo.BLL. T_Users bt1 = new BLL.T_Users();
DataSet ds = new DataSet();
ds = bt1.GetList(" T_UserEmail='" txtusername "'");
string cha = ds.Tables [0].Rows[0][0].ToString();
return "The email already exists, please re-enter";
}
catch {
return "Correct";
}
}