var vg = new VirtualGrid();

// listen for when new cells come into the view for the first time
vg.on("cellcreate", function(e){
  console.log(e.type, e);
});

// listen for when cells reenter the view
vg.on("cellenter", function(e){
  console.log(e.type, e);
});

// listen for when cells leave the view
vg.on("cellleave", function(e){
  console.log(e.type, e);
});

// add the grid to the map
vg.addTo(map);

var MyGrid = new VirtualGrid.extend({
  createCell: function(bounds, coords){
    console.log('create cell', bounds, coords);
  },

  cellEnter: function(bounds, coords){
    console.log('cell enter', bounds, coords);
  },

  cellLeave: function(bounds, coords){
    console.log('cell leave', bounds, coords);
  }
})

var thingWithGrid = new MyGrid().addTo(map);

var vg = new VirtualGrid({
  cellSize: 512,
  updateInterval: 150
});