Show comments with jquery - php

Question

I need create a function like a facebook comment. for example if i will click to comment button, it will show me all comments just from same post. i tried to create with jquery, but if i click to button it shows me all comments in all posts. I need just comments where i have clicked not others.
there is show_com.js:
$(".com_but").click(function() {
$('.all_com').show();
});
there is style css:
.all_com{
display:none;
}
and there is index.php:
<button class='com_but' id="<php echo $post_id; ?>">add comment</button>
<script src="show_com.js"></script>
<div class='all_com' id="<php echo $post_id; ?>">
<input type='text'/>
</div>
$post_id is id from post(like a facebook post or twitter).

Answer 1

$('.all_com').show(); will show all divs with class 'all_com', wherever they are on the page. But you seem to intend that you want only to display the 'all_coms' that are children of the same parent as the button clicked. Right?
In that case you should have something like:
<script src="show_com.js"></script>
<div class="container">
<button class='com_but' id="<php echo $post_id; ?>">add comment</button>
<div class='all_com' id="<php echo $post_id; ?>">
<input type='text'/>
</div>
</div>
and your function would be something like:
$(".com_but").click(function() {
$('.all_com',$(this).parent()).show();
});
this will only show elements of class all_com that are contained within the parent of the clicked button.
Hope this helps.

Answer 2

If you just want to show the comments that are within the same hierarchy as the click, the general way of doing that is go from the location of the click (denoted by $(this)) up to a common parent in that section of the DOM (using .closest(selector)), then find all items of interest in that common parent (using .find()).
You don't show enough of your HTML for us to know what that common parent selector would be, but the general idea is like this:
$(".com_but").click(function() {
$(this).closest(common parent selector here).find('.all_com').show();
});