ajax传递一个参数具体实现

!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
html xmlns="http://www.w3.org/1999/xhtml">
head>
title>/title>
script src="js/Jquery1.7.js" type="text/javascript">/script>
script type="text/javascript">
$(function () {
$('#txtUserName').blur(function () {
$.ajax({
type: "post",
contentType: "application/json",
url: "WebService1.asmx/ValidateUser",
data: "{username:'" + $('#txtUserName').val() + "'}",
success: function (result) {
$('#spinfo').text(result.d);
}
})
})
})
/script>
/head>
body>
div>
用户名input type="text" id="txtUserName" />span id="spinfo">/span>br />
密码input type="text" id="txtPwd" />
/div>
/body>
/html>