That's normal and it has nothing to do with the javascript.
That's because the pagination is stored in the session so that if you come back to the listing page later (for example from the product page), you are still on the same page.
You can change the line:
$pageInfo->limit->start = $app->getUserStateFromRequest( $this->paramBase.'.limitstart', 'limitstart_'.$this->params->get('main_div_name').$category_selected, 0, 'int' );
to:
$pageInfo->limit->start = JRequest::getVar('limitstart_'.$this->params->get('main_div_name').$category_selected, 0);
in the file components/com_hikashop/views/product/view.html.php and the current page won't be stored in the session.