Add nothing to react helpers

Author: vbfox

src/Fable.React/Fable.Helpers.React.fs

@@ -878,6 +878,10 @@ let inline ofList (els: ReactElement list): ReactElement = unbox(List.toArray el
 /// Returns an array **from .render() method**
 let inline ofArray (els: ReactElement array): ReactElement = unbox els
 
+/// A ReactElement when you don't want to render anything (null in javascript)
+[<Emit("null")>]
+let nothing: ReactElement = jsNative
+
 #else
 /// Alias of `ofString`
 let inline str (s: string): ReactElement = HTMLNode.Text s :> ReactElement
@@ -905,6 +909,9 @@ let inline ofList (els: ReactElement list): ReactElement = HTMLNode.List els :>
 /// Returns an array **from .render() method**
 let inline ofArray (els: ReactElement array): ReactElement = HTMLNode.List els :> ReactElement
 
+/// A ReactElement when you don't want to render anything (null in javascript)
+let nothing: ReactElement = HTMLNode.Empty :> ReactElement
+
 #endif