Update Blazor JS Interop for disposal (dotnet#16828)

Author: guardrex

aspnetcore/blazor/javascript-interop.md

@@ -504,7 +504,9 @@ returnArrayAsyncJs: function () {
 
 You can also call .NET instance methods from JavaScript. To invoke a .NET instance method from JavaScript:
 
-* Pass the .NET instance to JavaScript by wrapping it in a `DotNetObjectReference` instance. The .NET instance is passed by reference to JavaScript.
+* Pass the .NET instance by reference to JavaScript:
+  * Make a static call to `DotNetObjectReference.Create`.
+  * Wrap the instance in a `DotNetObjectReference` instance and call `Create` on the `DotNetObjectReference` instance. Dispose of `DotNetObjectReference` objects (an example appears later in this section).
 * Invoke .NET instance methods on the instance using the `invokeMethod` or `invokeMethodAsync` functions. The .NET instance can also be passed as an argument when invoking other .NET methods from JavaScript.
 
 > [!NOTE]
@@ -550,6 +552,68 @@ Console output in the browser's web developer tools:
 Hello, Blazor!
 ```
 
+To avoid a memory leak and allow garbage collection on a component that creates a `DotNetObjectReference`, dispose of the object in the class that created the `DotNetObjectReference` instance:
+
+```csharp
+public class ExampleJsInterop : IDisposable
+{
+    private readonly IJSRuntime _jsRuntime;
+    private DotNetObjectReference<HelloHelper> _objRef;
+
+    public ExampleJsInterop(IJSRuntime jsRuntime)
+    {
+        _jsRuntime = jsRuntime;
+    }
+
+    public ValueTask<string> CallHelloHelperSayHello(string name)
+    {
+        _objRef = DotNetObjectReference.Create(new HelloHelper(name));
+
+        return _jsRuntime.InvokeAsync<string>(
+            "exampleJsFunctions.sayHello",
+            _objRef);
+    }
+
+    public void Dispose()
+    {
+        _objRef?.Dispose();
+    }
+}
+```
+  
+The preceding pattern shown in the `ExampleJsInterop` class can also be implemented in a component:
+  
+```razor
+@page "/JSInteropComponent"
+@using BlazorSample.JsInteropClasses
+@implements IDisposable
+@inject IJSRuntime JSRuntime
+
+<h1>JavaScript Interop</h1>
+
+<button type="button" class="btn btn-primary" @onclick="TriggerNetInstanceMethod">
+    Trigger .NET instance method HelloHelper.SayHello
+</button>
+
+@code {
+    private DotNetObjectReference<HelloHelper> _objRef;
+
+    public async Task TriggerNetInstanceMethod()
+    {
+        _objRef = DotNetObjectReference.Create(new HelloHelper("Blazor"));
+
+        await JSRuntime.InvokeAsync<string>(
+            "exampleJsFunctions.sayHello",
+            _objRef);
+    }
+
+    public void Dispose()
+    {
+        _objRef?.Dispose();
+    }
+}
+```
+
 ## Share interop code in a class library
 
 JS interop code can be included in a class library, which allows you to share the code in a NuGet package.