Address bar commands that substitute a given argument in a URL when a given search key is used.

https://en.wikipedia.org/wiki/Smart_bookmark

For searching in Hacker news, I saved the URL 'https://hn.algolia.com/?query=%s' with the search key 'hn'. So when I want to search something around here, I just type

    hn something

which then replaces the %s variable with 'something'

   https://hn.algolia.com/?query=something

There is Javascript code that allows for two or more arguments, but saving that as a bookmarklet isn't as neat.