How to make voting through social networks vk/fb without share?

Question

JavaScript

You need to make a poll similar to this one www.nivea.ru/Experience/ext/ru-RU/katki-2015 Plz
explain the mechanics.
The essence is to arrange a similar vote, where to check 1 account = 1 vote, do not share and calculate the total number of vk / fb votes.

Answer 1

so everything is simple, votes are counted in php / js, only before voting, check (and record) for the uniqueness of the user ID. if it is not in the database - you can count this vote, if the ID has already voted - we send it to the forest).