title: How to load/unload markers based on visible tiles on Leaflet.js?
body: <p>According to the documentation I can pre-define the set of markers and other objects while creating the map, which then will be displayed. I do not wish to put all the possible markers/images/rectangles/etc in the JS code. I've read that people calculate the visible area on every tiles moving/zooming, do a HTTP request and server returns needed markers.</p>
  
  <p>However, I would like to use another way, as it is a little more efficient:</p>
  
  <p><strong>1.</strong> For example, currently Leaflet automatically asks for the tiles <strong>0:0</strong> and <strong>0:1</strong>;</p>
  
  <p><strong>2.</strong> In addition it could make a HTTP request and ask the server: "<em>Hey, give me also the markers for the tiles</em> <strong>0:0</strong> <em>and</em> <strong>0:1</strong>".</p>
  
  <p><strong>3.</strong> Completely remove markers which are on the tiles which have become invisible.</p>
  
  <p>Are the steps 2-3 possible and how if Yes?</p>