jQuery is not defined in Wordpress, but my script is enqueued properly

Question

I am trying to load a separate javascript file mobile-menu.js to my Wordpress theme. When I look at the console, it says, "jQuery is not defined." However, I know that I enqueued my script files correctly. Any ideas?

HTML file:

<a href="#" id="menu-icon"></a> <!--this line wasn't here originally-->
    <div id="switchmenu"><!--switchmenu begin-->
        <?php wp_nav_menu( array( 'theme_location' => 'primary' ) ); ?>
    </div><!--switchmenu end-->

functions.php file:

function lapetitefrog_scripts() {
    wp_enqueue_style( 'lapetitefrog-style', get_stylesheet_uri() );
    wp_enqueue_script( 'lapetitefrog-mobile-menu', get_template_directory_uri() . '/js/mobile-menu.js', array(), '1.0', true );
}
add_action( 'wp_enqueue_scripts', 'lapetitefrog_scripts' );

mobile-menu.js file:

 jQuery(document).ready(function($) {
    $('#menu-icon').click(function() {
            $('#switchmenu').slideToggle("fast");
    });
});

Answer 1

Add wp_enqueue_script('jquery'); before you enqueue your scripts.