//this goes in functions.php near the top
function my_scripts_method() {
// register your script location, dependencies and version
wp_register_script('custom_script',
get_template_directory_uri() . '/js/catalog.js',
array('jquery'),
'1.0' );
// enqueue the script
wp_enqueue_script('custom_script');
}
add_action('wp_enqueue_scripts', 'my_scripts_method');