Ajax中传递Json格式的参数

$.ajax({
type: "post",
    url: baseUrl+"sys/login",
    dataType: "json",
    contentType: "application/json;charset=utf-8",
data: JSON.stringify({userName: loginapp.userName,userPassword: loginapp.userPassword}),
　　
  或者拼接字符串的形式：
    data: "{\'userName\': \'"+loginapp.userName+"\',\'userPassword\': \'"+loginapp.userPassword+"\'}",