Multilingual landing (which way is right for SEO)?

Question

Search Engine Optimization

The task is to correctly implement a multilingual landing page in several languages.
I found 3 ways to implement it:
1) Subdomain (en.site.com) - Like a new site, which means an additional budget for promotion.
2) Subcategory (site.com/en) - Simple folder. (regular inclusion (with session IP redirect, to the desired folder))
3) Implementation method using code, an example like here: https://jsfiddle.net/yaskin/ozLyjts5/4/
All this suggests the idea of ​​Google indexing (and exactly the 3rd method)
If the site is originally in Russian and we write a language switch button without reloading the page, then what will Google see?
After all, the task is to capture as many requests from all languages ​​as possible with the same article.
What do you gentlemen advise?

Answer 1

so google has a doc about it
https://support.google.com/webmasters/answer/18219...

Answer 2

For Google, the second option is better. But definitely not worth embodying the third.

Answer 3

Yes, as the authors wrote, option 2 is the best in terms of price, quality and indexing will be better. Option 3, this is already a zakos for hidden content, and for this you can get people. And yes, do not forget about hreflang
And yes, that's how Peter wrote to you - link to Google of doc https://support.google.com/webmasters/answer/18219...