avoid refresh add to cart button

[strub]

Hi,

 

How can I avoid that the add to cart button refreshes the page site?

 

I want to add a onlick function which adds the product with ajax. Everything works except that it loads the page.

 

<?php echo tep_draw_button(IMAGE__IN_CART, null, null, 'primary', null, 'onClick="SBY.addToCart(' . $product_info['products_id'] . ')"'); ?>

 

Any ideas?

Thanks in advance