code: function (map) {
          this._map = map;
          this._canvas = L.DomUtil.create('canvas', 'leaflet-layer');
          this.tiles = {};
  
          var size = this._map.getSize();
          this._canvas.width = size.x;
          this._canvas.height = size.y;
  
          var animated = this._map.options.zoomAnimation && L.Browser.any3d;
          L.DomUtil.addClass(this._canvas, 'leaflet-zoom-' + (animated ? 'animated' : 'hide'));
  
  
          map._panes.overlayPane.appendChild(this._canvas);
  
          map.on(this.getEvents(), this);
  
          var del = this._delegate || this;
          del.onLayerDidMount && del.onLayerDidMount(); // -- callback
  
          this.needRedraw();
      }
docs: -------------------------------------------------------------