code: function () {
  		var i, tile;
  		for (i in this._tiles) {
  			if (this._tiles[i].coords.z !== this._tileZoom) {
  				tile = this._tiles[i].el;
  
  				tile.onload = L.Util.falseFn;
  				tile.onerror = L.Util.falseFn;
  
  				if (!tile.complete) {
  					tile.src = L.Util.emptyImageUrl;
  					L.DomUtil.remove(tile);
  				}
  			}
  		}
  	}
docs: stops loading all tiles in the background layer