Where should I place my Easy Slider jQuery functions in my Wordpress theme?

Question

I added Easy Slider to my Wordpress blog. The problem is that the buttons are even shown when there's a Page with no slider or pictures.

I used to place this:

$(document).ready(function () {
 //easy slider
 $("#slider").easySlider({
  auto: true,
  continuous: true
 });
});

in a custom.js file which I placed in Wordpress's footer.php file but since the footer is included in every page, the buttons of Easy Sliders are being generated in every page.

I tried placing that function right before get_footer() in index.php but the easy Slider stopped working.

Any suggestions?