从提交ID进行ajax调用

Question

I have a form in which currently posts to a hard coded php page in the action of the form, this works fine, it posts to the DB no problem, but where things get tricky for me is I don't want to post to a new page so I have opted to use ajax. So I got rid of the action field from the form and put in some jquery to make an ajax call. the issues I am having is well..it doesn't work :D. Could someone take a look at my js file and explain to me what I am doing wrong or what I should do?

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js" type="text/javascript">

  <form>
      <p>Comment</p>
      <textarea name= "comment" rows="6" cols="50"></textarea><br />
      <input type="submit" name= "submit" value="submit" id = "submit">
    </form>

$('#submit').on('click',function(){
       $.ajax({
            type        : 'POST',
            url         : 'comment.php',
            data        : formData,
            dataType    : 'json',
      })
   });

</div>