请解决我的AJAX脚本中的联系表格问题

我正在尝试实现一些AJAX脚本，通过该脚本我的“联系我们”表单无需刷新页面即可提交

我已经尝试了很多，因为我不知道我的AJAX代码中的错误在哪里。

这是我的index.php文件

<div id="response_result">
</div>

<form class="contact-form" method="POST" action="" onsubmit="return foo();" name="form" id="form_id">
            <input type="text" name="contact_name" id="contact_name_id" />
            <input type="text" name="contact_email" id="contact_email_id" />
            <input type="text" id="contact_phone_id" name="contact_phone" />
            <input type="text" id="contact_company_name_id" name="contact_company_name"/>
            <input type="text" name="contact_subject" id="contact_subject_id"/> 
            <textarea name="contact_message" id="contact_message_id"></textarea>
            <input type="submit" name="contact_submit" value="Submit Message" id="contact_submit_id" /> 
</form>

这是我针对该文件的PHP代码

<?php
if(isset($_POST['contact_submit']))
{
    $contact_name = $_POST['contact_name'];
    $contact_email = $_POST['contact_email'];
    $contact_phone = $_POST['contact_phone'];

    $contact_company_name = $_POST['contact_company_name'];

    $contact_subject = $_POST['contact_subject'];
    $contact_message = $_POST['contact_message'];

    if ((strlen($contact_message) < 5) OR (strlen($contact_message) > 500))
    {
        ?>
        <script>
        alert('Your Message Should contains Characters between 5 to 500 ..... !!');
        </script>
        <?php
        return false;
    }

    else if(($contact_name == "") OR ($contact_email == "") OR ($contact_phone == "") OR ($contact_company_name == "") OR ($contact_subject == "") OR ($contact_message == ""))
    {
        ?>
        <script>
        alert('Please Supply Each Field .... !!');
        </script>
        <?php
    }

    else if($Object->save_contact_us_form_data($contact_name, $contact_email,$contact_phone, $contact_company_name, $contact_subject, $contact_message, $contact_date))
    {
        ?>
        <script>
        alert('Data Submitted Successfully .... !!\nWe will get Back You Soon .... !!');
        </script>
        <?php
        return true;
    }

    else
    {
        ?>
        <script>
        alert('An Error Occured While Submitting Data .... !!');
        </script>
        <?php
        return false;
    }
}
?>

我的PHP代码运行完美。

这是我的AJAX代码（无效）

<script>
   function foo()
   {
      var contact_name1 = document.getElementById( "contact_name_id" ).value;
      var contact_email1 = document.getElementById( "contact_email_id" ).value;
      var contact_phone1 = document.getElementById( "contact_phone_id" ).value;
      var contact_company_name1 = document.getElementById( "contact_company_name_id" ).value;
      var contact_subject1 = document.getElementById( "contact_subject_id" ).value;
      var contact_message1 = document.getElementById( "contact_message_id" ).value;
      $.ajax({
         type: 'post',
         url: 'Contact_Us.php',
         data: {
            contact_name:contact_name1,
            contact_email:contact_email1,
            contact_phone:contact_phone1,
            contact_company_name:contact_company_name1,
            contact_subject:contact_subject1,
            contact_message:contact_message1
         },
         success: function (response) {
            document.getElementById( "response_result" ).innerHTML = response;
         }
      });
   }
</script>