How to avoid reloading page on sending a file? [closed]

I’ve written a small application using HTML, JavaScript, and Node.js that allows saving strings to a database and a file on a server. However, the file upload is accompanied by an unwanted page reload. Can you please help me?

Here’s my repository :https://github.com/krommmm/unwantedReloadPage.git

I’m expecting the page to no reload on post fetch