使用带有var附加的$.ajax数据发送repatcha响应

我有一个带有$.ajax的表单帖子用于验证。它在POST上为"data:"使用一个变量，并将信息附加到变量中的分隔值中，然后在服务器端php上检索它们。工作很好，但我正在尝试将我的reCaptcha响应添加到数据流中，以将其添加到php端。我尝试过很多场景，但到目前为止都没有成功。如果有人有一个想法，那就太棒了！！这里有一个java片段：

$(document).ready(function() {
            $("#submit_btn").click(function() { 
                //var reCaptcha = grecaptcha.getResponse();
                //alert(reCaptcha); // --> captcha response:
                var proceed = true;
                //simple validation at client's end
                //loop through each field and we simply change border color to red for invalid fields       
                $("#contact_form input[required=true], #contact_form textarea[required=true]").each(function(){
                    $(this).css('border-color',''); 
                    if(!$.trim($(this).val())){ //if this field is empty 
                        $(this).css('border-color','red'); //change border color to red   
                        proceed = false; //set do not proceed flag
                    }
                    //check invalid email
                    var email_reg = /^(['w-'.]+@(['w-]+'.)+['w-]{2,4})?$/; 
                    if($(this).attr("type")=="email" && !email_reg.test($.trim($(this).val()))){
                        $(this).css('border-color','red'); //change border color to red   
                        proceed = false; //set do not proceed flag              
                    }   
                });
                if(proceed) //everything looks good! proceed...
                {
                   //data to be sent to server 
                   var reCaptcha = grecaptcha.getResponse();         
                    var m_data = new FormData();    
                    m_data.append( 'user_name', $('input[name=name]').val());
                    m_data.append( 'user_email', $('input[name=email]').val());
                    m_data.append( 'country_code', $('input[name=phone1]').val());
                    m_data.append( 'phone_number', $('input[name=phone2]').val());
                    m_data.append( 'subject', $('select[name=subject]').val());
                    m_data.append( 'msg', $('textarea[name=message]').val());
                    m_data.append( 'file_attach', $('input[name=file_attach]')[0].files[0]);
                    m_data.append( 'recaptcha', $(reCaptcha).val());

                    //instead of $.post() we are using $.ajax()
                    //that's because $.ajax() has more options and flexibly.
                    $.ajax({
                      url: 'contact_me.php',
                      data: m_data,
                      processData: false,
                      contentType: false,
                      type: 'POST',
                      dataType:'json',
                      success: function(response){
                         //load json data from server and output message     
                        if(response.type == 'error'){ //load json data from server and output message     
                            output = '<div class="error">'+response.text+'</div>';
                        }else{
                            output = '<div class="success">'+response.text+'</div>';
                        }
                        $("#contact_form #contact_results").hide().html(output).slideDown();
                      }
                    });

                }
            });

这是PHP:

//check if its an ajax request, exit if not
if(!isset($_SERVER['HTTP_X_REQUESTED_WITH']) AND strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) != 'xmlhttprequest') {
    $output = json_encode(array( //create JSON data
        'type'=>'error',
        'text' => 'Sorry Request must be Ajax POST'
    ));
    die($output); //exit script outputting json data
}

//Sanitize input data using PHP filter_var().
$user_name      = filter_var($_POST["user_name"], FILTER_SANITIZE_STRING);
$user_email     = filter_var($_POST["user_email"], FILTER_SANITIZE_EMAIL);
$country_code   = filter_var($_POST["country_code"], FILTER_SANITIZE_NUMBER_INT);
$phone_number   = filter_var($_POST["phone_number"], FILTER_SANITIZE_NUMBER_INT);
$subject        = filter_var($_POST["subject"], FILTER_SANITIZE_STRING);
$message        = filter_var($_POST["msg"], FILTER_SANITIZE_STRING);
$captcha        = filter_var($_POST["recaptcha"], FILTER_SANITIZE_STRING);


if(strlen($user_name)<4){ // If length is less than 4 it will output JSON error.
    $output = json_encode(array('type'=>'error', 'text' => $captcha));
    die($output);
}

我需要做的是将响应输入PHP，添加到我的密钥中，其余部分继续验证reCaptcha。我所做的是，我试图将reCaptcha响应捆绑到中

m_data.append( 'recaptcha', $(reCaptcha).val());

然后用提取

$captcha = filter_var($_POST["recaptcha"], FILTER_SANITIZE_STRING);

然后看看它是否会显示在我的错误字段中，因为名称太短：

if(strlen($user_name)<4){ // If length is less than 4 it will output JSON error.
    $output = json_encode(array('type'=>'error', 'text' => $captcha));
    die($output);
}

请帮忙！