How can i transform an HTML form response to another HTML page and display it using Javascript?

I've tried for hours to figure this out, Quick context is that i wanted to make a reCAPTCHA test site here: https://paecraft.github.io/ and make it display the results of each form variable, being the problem that PHP is not supported on github pages. I'll try to figure it out but i'd be happy if you could help! :)