ok ovo je html
<div class='comments'>
<img src='uploads/$row[userPhoto]' width='40' height='40'>
<textarea class='commentText' id='" . $row_post["commentID"]. "' name='postText' placeholder='Write a comment...'></textarea>
</div>
i ovo je js
$(.commentText).keypress(function(e) {
   var post_id= $(this).attr('id');
    if(e.which == 13) {
        alert('Button succeed!');
    }
});