Add JavaScript file to our body.

functions.php

<?php
//* Do NOT include the opening PHP tag

/** 
  * Include the JavaScript
  * @author Calvin Koepke (@cjkoepke)
  * @link http://www.calvinkoepke.com/add-a-mobile-friendly-off-canvas-menu-in-genesis
*/
add_action( 'wp_enqueue_scripts', 'ck_load_menu' );
function ck_load_menu() {
  
  wp_enqueue_script( 'ck-menu', get_stylesheet_directory_uri() . '/js/offcanvas-nav.js', array( 'jquery' ), 1.0 );

  //* Also include Dashicons for the iconography
  wp_enqueue_style( 'dashicons' );

}