AJAX Query Post fileds

I have the following code to produce a button with a unique ID of the related Wordpress post (there are several of these links); <div id="<?php echo $post->ID ;?>" class="button buy">Buy Now</div> When clicked, this needs to run an external PHP file and run a query based on the post id of the link. Ideally, something like this; <?php $post = get_post($post->ID);?> <a href="<?php the_field('itunes_link') ;?>">Buy Now</a> <?php wp_reset_query() ;?> I need someone to write the AJAX function to get the $post->ID of the clicked button, store as variable and use that to run the query. The returning data will be used within a popup. I had attempted this myself, but getting the $post->ID as a variable is something I do not know how to do! Here's my existing AJAX; jQuery(".buy").on('click', function(){ [login to view URL]({ url: '<?php echo get_stylesheet_directory_uri(); ?>/ajax/[login to view URL]', success: function (data) { [login to view URL]("popup").innerHTML = data; }, error: function (xhr, status, error) { if ([login to view URL] > 0) [login to view URL]("popup").innerHTML = ('Error: ' + status); } }); }); I hope that makes sense. Please ask if you have any questions.