why my custom js is not loading in wordpress code example

Example: wordpress not loading jquery

function include_jQuery() {
    if (!is_admin()) {
        // comment out the next two lines to load the local copy of jQuery
        wp_deregister_script('jquery'); 
        wp_register_script('jquery', 'http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js', false, '1.8.3'); 
        wp_enqueue_script('jquery');
    }
}
add_action('init', 'include_jQuery');