What is the best way to make a map with a real user display location?

Question

OpenStreetMap

Good evening, dear geeks :)
Help / tell me or direct me on the right path)
1. Need a map, preferably OSM (due to OpenSource)
2. Need to display a map with the location of users (if they clicked the "Allow" button) if not, do not display the map .
That is, if it is logical to think, then the function of displaying the location is private, because on the map we see only our location, but how to make it all public with reference to the site on which, in principle, this map exists?
3. The map should not scroll, while you need a "logical" grouping of points-users and, depending on the number of users or a point, increase or change its color or write a number at a point.
Ideally, the entire map of the world should be visible. but so that the map is not "cluttered" with points, they need to be "logically" grouped (example on the screen, the point and radius from which to take the location)
4. The user must be displayed on the map when he is on the site and for example, no longer than 5 minutes after the user left website.
5. It is desirable that everything happens "in real time" ie without refreshing the page.
Tell me what is better to use, what can be "collected", while performance is important for everyone (so that the site does not suffer)

PS I came across such a thing in the Yandex API
https://tech.yandex.ru/maps/jsbox/2.0/clusterer_gr...
In principle, if you get what you need, but points 2, 4 and 5 remain. And before all this, how to properly map everyone who is on the site, where to save them?
If so, then this is the same Yandex.Taxi card. Tell me how to organize it for "static" objects and point 4 remains.

Answer 1

1. You use leafletjs.com
2. You use some geoip plugin, at least on the server, at least on the client, which then throws them off the server.
3. Use the clustering plugin leafletjs.com/plugins.html#clusteringdecluttering , although Heatmaps would be better here

Answer 2

https://habrahabr.ru/company/yandex/blog/243665/