Is there a way to know what is the url before it will be encoded?

I want to know if there is a way to know the inputted URL before encoding.

My problem is once i enter the URL, the space automatically encodes to %20. For example i have a URL that has this parameter ?a=on e

I need to get this string "a=on e" , because i need to differentiate whether the user input is a space or %20.

Thank you in advance for your answers