I’m using Smartwave Porto theme for my Magento 2 website. When I load my website for the first time it’s loading properly, but every time I refresh the browser page it will show an error like this in browser console and my page does not load properly:

Uncaught TypeError: $(...).swMegamenu is not a function
Uncaught TypeError: $(...).stellar is not a function
Uncaught TypeError: $(...).owlCarousel is not a function
Uncaught TypeError: $.widget is not a function

I just do below changes :

Create a requirejs-config.js in the root of the child theme (you can also do this on root theme if you have not created a child theme) as per Porto child like this:

app/design/frontend/Smartwave/porto_child and add the following code in it:

var config = {
    shim: {
        jquery: {
            exports: '$'
        },
        'Smartwave_Megamenu/js/sw_megamenu':
            {
                deps: ['jquery']
            }, 
        'owl.carousel/owl.carousel.min':
            {
                deps: ['jquery']
            },
        'js/jquery.stellar.min': 
            {
            deps: ['jquery']
            },
        'js/jquery.parallax.min':
            {
            deps: ['jquery']
            }
    }
};

And also change child theme layout file at:

app/design/frontend/Smartwave/porto_child/Magento_Theme/layout/default_head_blocks.xml

From:

<script src="jquery.js" />
<script src="bootstrap/js/bootstrap.min.js" />
<script src="fancybox/js/jquery.fancybox.js" />

To:

<remove src="jquery.js" />
<remove src="bootstrap/js/bootstrap.min.js" />
<remove src="fancybox/js/jquery.fancybox.js" />

I don’t need the fancybox, So I have turned it off, but if you require it, I guess it should be included in the requirejs as well. If you face the same issue, follow the above steps to solve it.