Give a Warning if Users Did not Submit the Form before leaving the page

We have the Jotform being used for submitting images for customizations of their products, however, some people are adding the products to the cart and not actually hitting Submit on their form - is there a way to produce a warning before the page is refreshed  upon adding to cart to warn them that they did not submit the form?

I would like to apologize, but I'm afraid that we don't have a feature on the builder page to show a warning message when respondents decided to close their browser or reload the page.

As a workaround, you can embed your form on your website and create a script that will show a warning message when the user tries to reload the page or close the browser. — https://forums.asp.net/t/1521439.aspx?How+to+check+when+user+click+close+back+refresh+button+in+browser+and+popup+the+message+

Here's a sample — show-warning-when-closed

If you have other questions, please do not hesitate to let us know.

 I don't get any warning on Chrome from that sample, it just lets me close it @_@ lol

Unfortunately, there is not such a feature that prompts the user just before the form page is closed without any submission yet. 
I recommend you to download the source code of the form and apply script codes in order to achieve this requirement.

How to get the Full Source Code of your Form