WordPress: Add dropdown menu on search?

Question

Actual I am searching for a plugin or a way to program a plugin which shows a drop down menu if a user is typing some chars in the search box.

As you know it from Google, Facebook or Co. You are searching for something and get the actual "results" or suggestions. And every time you type a new char, the suggestions got refreshed.

Does anybody know how it works and maybe how I can program that?

I mean, the difference is just to start a search after every char instand of at the end by pressing enter.

Greetings and Thank You!

Answer 1

https://wordpress.org/plugins/search-filter/screenshots/

This plugin is used for auto fielter. I hope this will help you.