php - How to properly get loading text display based on the like button click via jQuery

Solution:

You need to get the loader in relation to the clicked button so instead of using

$('.loader')

Use

$(this).parent().find('.loader')

Same goes for your result message.

The following is a modified click function:

$('.like_post').click(function(e) {
  // as you are doing an ajax post here, I would disable the default action of the button:
  e.preventDefault();

  var $button = $(this);  // you use this multiple times so it is more efficient to put it in a var
  
  var id = $button.data('id');
  
  var $buttParent = $button.parent();
  var $loader = $buttonParent.find('.loader');

  $loader.html('<div style="background:green;color:white;padding:6px;">Please Wait, sending like...</div>').fadeIn(400);  // I would change the html before the fadeIn
  
  var rec = {
    id: id
  };

  $.ajax({
    type: 'POST',
    url: 'like_rec.php',
    data: rec,
    cache: false,
    success: function(msg) {
      $loader.hide();
      $buttonParent.find('.result_like').html(msg);
    }
  });
});

Also the center tag is obsolete so don't use it, instead give your heading a class and use css to centre the text

Solution:

You're currently targeting every "loader" and every "result_like":

$('.loader').hide();
$('.result_like').html(msg);

Since the elements you want to target are all contained within a single parent <div>, you can use that for jQuery DOM traversal. Starting from the element being clicked, you can navigate to the containing <div> and then back down to the target element(s). Something like this:

$(this).parent('div').find('.loader').hide();
$(this).parent('div').find('.result_like').html(msg);

To be repeated anywhere you want to target an element within that "group" of elements. You could also store the containing <div> in a variable if you prefer, which comes with a tiny performance improvement:

var container = $(this).parent('div');

//...

container.find('.loader').hide();
container.find('.result_like').html(msg);