diff --git a/aspnetcore/blazor/javascript-interop.md b/aspnetcore/blazor/javascript-interop.md
index e647530c86..1befbb906d 100644
--- a/aspnetcore/blazor/javascript-interop.md
+++ b/aspnetcore/blazor/javascript-interop.md
@@ -5,7 +5,7 @@ description: Learn how to invoke JavaScript functions from .NET and .NET methods
 monikerRange: '>= aspnetcore-3.0'
 ms.author: riande
 ms.custom: mvc
-ms.date: 05/21/2019
+ms.date: 05/29/2019
 uid: blazor/javascript-interop
 ---
 # Blazor JavaScript interop
@@ -101,6 +101,10 @@ The sample app includes a component to demonstrate JavaScript interop. The compo
 1. The `showPrompt` function accepts user input (the user's name), which is HTML-encoded and returned to the component. The component stores the user's name in a local variable, `name`.
 1. The string stored in `name` is incorporated into a welcome message, which is passed to a JavaScript function, `displayWelcome`, which renders the welcome message into a heading tag.
 
+## Call a void JavaScript function
+
+JavaScript functions that return [void(0)/void 0](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Operators/void) or [undefined](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/undefined) are called with `IJSRuntime.InvokeAsync<object>`, which returns `null`.
+
 ## Detect when a Blazor app is prerendering
  
 [!INCLUDE[](~/includes/blazor-prerendering.md)]