Using multiple popup windows with bPopup
He is right.  Think about maintenance.  

If you wanted to add another link that popped up another element you would need to add yet another listener function.  Removing one would be the same thing.  Too many things to keep track of.

Change the code to add the event according to a class name and then you can bind to all at once.  Then include the popup element ID within the attributes of the opener link.

$('.popup-opener').bind('click', function(e) {
    e.preventDefault();
    $($(this).attr('popup-element')).bPopup();
});

&lt;!-- Button that triggers the popup --&gt;
&lt;a class="main popup-opener" popup-element="element_to_pop_up_1" id="my-button_1" href="#"&gt;Popup 1&lt;/a&gt;&lt;/b&gt;&lt;br /&gt;
&lt;!-- Element to pop up --&gt;
&lt;div id="element_to_pop_up_1"&gt;
// ...
&lt;/div&gt;


Better yet, use the on() function to bind the event.  http://api.jquery.com/on/

Adding new openers now requires no changes to the javascript.