Как мне...установить язык веб-сайта(navbar и т. д.) самым лучшим образом?

I do have, a Navbar with two options in the German language that look as the following:

Erste| Zweit, Erste = First, Zweite = Second, 

What will be the best Practice for translating this Page, based on the region of visit?

My Attempt:

In the JS - File, find out the Region, if - English speaking, setText for all the options to English.

Is there a possibility to add all the Regions-Translations to a formatter - File and to access Information for HTML-Elements, along this lines: text="formatter/eng" ?