How can I add the Post ID to Class Name in Jquery?

You are using css to display none we don’t need to use show() function.

Please click on javascript icon in fiddle and select any jquery1.9.1 or above version . Update this code and run ( http://screenshotlink.ru/8f491216a33e437f762eb8815efec77d.png )

$(document).ready(function(){

   $('.share-icon').on('click',function (e) {
       var id = $(this).attr("id").split('-'); 
      $('.post-share#post-share-'+id[2]).css("display","block");
   });

});