CODE EXAMPLE FOR PHP

wordpress theme directory uri

add_action('wp_enqueue_scripts', 'wpdocs_scripts_method');
 
/*
 * Enqueue a script with the correct path.
 */
function wpdocs_scripts_method() {
    wp_enqueue_script(
        'custom_script',
        get_template_directory_uri() . '/js/custom_script.js',
        array('jquery')
    );
}