Adding removing layers dynamically (#42)

* Supporting adding and remoing google layers dynamically

* Fixed naming

Author: aviklai

src/index.ts

@@ -36,5 +36,38 @@ const createLeafletElement = (props: IProps, context: LeafletContextInterface) =
   return { instance, context };
 }
 
+const updateLeafletElement = (
+  instance: L.GridLayer,
+  props: IProps,
+  prevProps: IProps
+) => {
+  let prevGoogleMapsAddLayers = prevProps.googleMapsAddLayers
+    ? prevProps.googleMapsAddLayers.map((addLayer: IGoogleMapsAddLayer) => addLayer.name)
+    : [];
+  let currentGoogleMapsAddLayers = props.googleMapsAddLayers
+    ? props.googleMapsAddLayers.map((addLayer: IGoogleMapsAddLayer) => addLayer.name)
+    : [];
+  if (props.googleMapsAddLayers) {
+    props.googleMapsAddLayers.forEach((layer) => {
+      if (prevGoogleMapsAddLayers.indexOf(layer.name) === -1) {
+        (instance as L.gridLayer.GoogleMutant).addGoogleLayer(
+          layer.name,
+          layer.options
+        );
+      }
+    });
+  if (prevProps.googleMapsAddLayers) 
+    prevProps.googleMapsAddLayers.forEach((layer) => {
+      if (currentGoogleMapsAddLayers.indexOf(layer.name) === -1) {
+        (instance as L.gridLayer.GoogleMutant).removeGoogleLayer(layer.name);
+      }
+    });
+  }
+
+  updateGridLayer(instance, props, prevProps);
+};
 
-export default createLayerComponent<L.GridLayer, LayerProps & IProps>(createLeafletElement, updateGridLayer);
+export default createLayerComponent<L.GridLayer, LayerProps & IProps>(
+  createLeafletElement,
+  updateLeafletElement
+);