Answer 1

Give button a type. If you omit type attribute, it will be submit button by default.

Answer 2

Mirielle you are not directed to the blank page. You are directed to same page with form input values in url. See link https://stackoverflow.com/questions/2314401/what-is-the-default-form-http-method#:~:text=The%20default%20%27method%27%2C%20%27,www%2Dform%2Durlencoded%20respectively.

Answer 3

There is nothing wrong with your code. If you use sololearn website but not android app. its buggy, it throws error.

I suggest use jsfiddle.net when you are at your computer

https://jsfiddle.net