同步检索ajax数据回调用函数

Question

我的表单中包含google验证码：http://code.google.com/p/cool-php-captcha。

由于此验证码使用会话来存储验证码，因此我很难通过ajax将会话的最新变量检索到javascript中。当我的ajax命令使用async：false标志时，它运行良好，但由于这是折旧的，我宁愿不使用它。

我目前的问题是我正在尝试使用回调函数来检索值但是通过尝试将值发送回原始函数我在我的2个函数之间创建了一个循环并且不能完全找出获得我想要的最佳方式。

感谢任何帮助欢呼Callum

<script type="text/javascript">

function getcaptchsession()
{
 $.ajax({url:'/Includes/Session.php', cache:false, type: 'GET', success:function(data, status, XHR){validate(data);}});
}

function validate(data)
{
 var session = data;
 var ok = '';
 var nameerror = '';
 var emailerror = '';
 var subjecterror = '';
 var messageerror = '';
 var contactform = document.forms.ContactForm;
 var fullname = contactform.Fullname.value;
 var emailadd = contactform.Emailadd.value;
 var subject = contactform.Subject.value;
 var message = contactform.Message.value;
 var captcha = contactform.CaptchaText.value;

getcaptchsession();

if (fullname == "")
{
 var x = document.getElementsByClassName("error");
 x[0].innerHTML = "Name field is a required field.";
 nameerror = true;
}
else if (fullname != "")
{
 if (/[^a-z\s-]/i.test(fullname))
 {
  var x = document.getElementsByClassName("error");
  x[0].innerHTML = "Alphabetic characters only.";
  nameerror = true;
 }
 else
 {
  var x = document.getElementsByClassName("error");
  x[0].innerHTML = "";
  nameerror = false;
 }
}

if (emailadd == "")
{
 var x = document.getElementsByClassName("error");
 x[1].innerHTML = "Email field is a required field.";
 emailerror = true;
}
else if (emailadd != "")
{
 if (/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(emailadd))
{
 var x = document.getElementsByClassName("error");
 x[1].innerHTML = "";
 emailerror = false;
}
else
{
 var x = document.getElementsByClassName("error");
 x[1].innerHTML = "Email is not a valid email address.";
 nameerror = true;
}
}

if (subject == "")
{
var x = document.getElementsByClassName("error");
x[2].innerHTML = "Subject field is a required field.";
subjecterror = true;
}
else
{
var x = document.getElementsByClassName("error");
x[2].innerHTML = "";
subjecterror = false;
}

if (message == "")
{
var x = document.getElementsByClassName("error");
x[3].innerHTML = "Message field is a required field.";
messageerror = true;
}
else
{
 var x = document.getElementsByClassName("error");
 x[3].innerHTML = "";
 messageerror = false;
}

if (captcha == "")
{
 var x = document.getElementsByClassName("error");
 x[4].innerHTML = "The captcha field is a required field.";
 messageerror = true;
}
else if (captcha != "")
{
 if (captcha != session)
 {
  var x = document.getElementsByClassName("error");
  x[4].innerHTML = "Captcha mismatch.";
  messageerror = true;
 }
 else
 {
  var x = document.getElementsByClassName("error");
  x[4].innerHTML = "";
  messageerror = false;
 }
}
if (nameerror == true || emailerror == true || subjecterror == true || messageerror == true || captcha == true)
{
 return false;
}
else
{
 return true;
}
 }
</script>

我的表格如下：

<form id="ContactForm" name="ContactForm" action="javascript:loadDoc();" onsubmit="return(validate());">
 <label for="Fullname">Name <span class="red">*</span><span class="error"></span></label>
 <input id="ContactFormInput" name="Fullname" class="text" id="Fullname">
 <label for="Emailadd">Email <span class="red">*</span><span class="error"></span></label>
 <input id="ContactFormInput" name="Emailadd" class="text" id="Emailadd">
 <label for="Subject">Subject <span class="red">*</span><span class="error"></span></label>
 <input id="ContactFormInput" name="Subject" class="text" id="Subject">
 <label for="Message">Message <span class="red">*</span><span class="error"> </span></label>
 <textarea id="Message" name="Message" rows="6" cols="30"></textarea>
<label for="CaptchaText" id="captchalabel">Captcha <span class="red">*</span><span class="error"></span></label>
<div id="CaptchaParent">
<div id="CaptchaIframe">
<img src="/Includes/captcha.php" id="captcha" />
</div><div id="CaptchaReload">
<img class="captchareload" src="/Images/Contact_Us/reload_icon.png" onclick="document.getElementById('captcha').src='/Includes/captcha.php?'+Math.random()">
</div><div id="CaptchaInput">
<input name="CaptchaText" id="CaptchaText" maxlength="8" class="text">
</div>
</div>
<div id="ContactInput">
<input id="Submit" class="ContactButton" type="submit" name="submit" class="button" value="Send Now"/>
</div>
</form>

我的php会话页面有

<?php
session_start();

echo $_SESSION['captcha'];
?>