Improve DotNetStreamReference disposal remarks (#33036)

aspnetcore/blazor/javascript-interoperability/call-javascript-from-dotnet.md

@@ -1213,14 +1213,14 @@ For information on using a byte array when calling .NET from JavaScript, see <xr
 
 ## Stream from .NET to JavaScript
 
-Blazor supports streaming data directly from .NET to JavaScript. Streams are created using a <xref:Microsoft.JSInterop.DotNetStreamReference>.
+Blazor supports streaming data directly from .NET to JavaScript (JS). Streams are created using a <xref:Microsoft.JSInterop.DotNetStreamReference>.
 
 <xref:Microsoft.JSInterop.DotNetStreamReference> represents a .NET stream and uses the following parameters:
 
-* `stream`: The stream sent to JavaScript.
+* `stream`: The stream sent to JS.
 * `leaveOpen`: Determines if the stream is left open after transmission. If a value isn't provided, `leaveOpen` defaults to `false`.
 
-In JavaScript, use an array buffer or a readable stream to receive the data:
+In JS, use an array buffer or a readable stream to receive the data:
 
 * Using an [`ArrayBuffer`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer):
 
@@ -1241,15 +1241,24 @@ In JavaScript, use an array buffer or a readable stream to receive the data:
 In C# code:
 
 ```csharp
-using var streamRef = new DotNetStreamReference(stream: {STREAM}, leaveOpen: false);
+var streamRef = new DotNetStreamReference(stream: {STREAM}, leaveOpen: false);
 await JS.InvokeVoidAsync("streamToJavaScript", streamRef);
 ```
 
 In the preceding example:
 
-* The `{STREAM}` placeholder represents the <xref:System.IO.Stream> sent to JavaScript.
+* The `{STREAM}` placeholder represents the <xref:System.IO.Stream> sent to JS.
 * `JS` is an injected <xref:Microsoft.JSInterop.IJSRuntime> instance.
 
+Disposing a <xref:Microsoft.JSInterop.DotNetStreamReference> instance is usually unnecessary. When `leaveOpen` is set to its default value of `false`, the underlying <xref:System.IO.Stream> is automatically disposed after transmission to JS.
+
+If `leaveOpen` is `true`, then disposing a <xref:Microsoft.JSInterop.DotNetStreamReference> doesn't dispose its underlying <xref:System.IO.Stream>. The app's code determines when to dispose the underlying <xref:System.IO.Stream>. When deciding how to dispose the underlying <xref:System.IO.Stream>, consider the following:
+
+* Disposing a <xref:System.IO.Stream> while it's being transmitted to JS is considered an application error and may cause an unhandled exception to occur.
+* <xref:System.IO.Stream> transmission begins as soon as the <xref:Microsoft.JSInterop.DotNetStreamReference> is passed as an argument to a JS interop call, regardless of whether the stream is actually used in JS logic.
+
+Given these characteristics, we recommend disposing the underlying <xref:System.IO.Stream> only after it's fully consumed by JS (the promise returned by `arrayBuffer` or `stream` resolves). It follows that a <xref:Microsoft.JSInterop.DotNetStreamReference> should only be passed to JS if it's unconditionally going to be consumed by JS logic.
+
 <xref:blazor/js-interop/call-dotnet-from-javascript#stream-from-javascript-to-net> covers the reverse operation, streaming from JavaScript to .NET.
 
 <xref:blazor/file-downloads> covers how to download a file in Blazor.