Trailing slash before a query string. Bad practice?

Question

I have a URL like www.example.com/store/, which leads to a store page

When a user clicks on a discount link, it adds the parameter ?discount=foo, so my link looks like this: www.example.com/store/?discount=foo.

Everything is functional. But is it bad practice to have the forward slash before the query string in this situation?

Answer 1

It’s valid:

1. The path component may end with a slash (/).
2. The query component starts with the first question mark (?) in the URI.