Enable IJSObjectReference to handle null/undefined values

src/JSInterop/Microsoft.JSInterop.JS/src/src/Microsoft.JSInterop.ts

@@ -155,6 +155,12 @@ export module DotNet {
    * @throws Error if the given value is not an Object.
    */
   export function createJSObjectReference(jsObject: any): any {
+      if (jsObject === null || jsObject === undefined) {
+          return {
+              [jsObjectIdKey]: -1
+          };
+      }
+
       if (jsObject && (typeof jsObject === "object" || jsObject instanceof Function)) {
           cachedJSObjectsById[nextJsObjectId] = new JSObject(jsObject);
 
@@ -220,7 +226,7 @@ export module DotNet {
   export function disposeJSObjectReference(jsObjectReference: any): void {
       const id = jsObjectReference && jsObjectReference[jsObjectIdKey];
 
-      if (typeof id === "number") {
+      if (typeof id === "number" && id !== -1) {
           disposeJSObjectReferenceById(id);
       }
   }

src/JSInterop/Microsoft.JSInterop.JS/src/test/CallDispatcher.test.ts

@@ -395,4 +395,25 @@ describe("CallDispatcher", () => {
 
         expect(result2).toBe("30");
     });
+
+    test("createJSObjectReference: Handles null values without throwing", () => {
+        const nullRef = DotNet.createJSObjectReference(null);
+        expect(nullRef).toEqual({ [jsObjectId]: -1 });
+    });
+
+    test("createJSObjectReference: Handles undefined values without throwing", () => {
+        const undefinedRef = DotNet.createJSObjectReference(undefined);
+        expect(undefinedRef).toEqual({ [jsObjectId]: -1 });
+    });
+
+    test("disposeJSObjectReference: Safely handles null reference disposal", () => {
+        const nullRef = DotNet.createJSObjectReference(null);
+        expect(() => DotNet.disposeJSObjectReference(nullRef)).not.toThrow();
+    });
+
+    test("createJSObjectReference: Still throws for invalid types", () => {
+        expect(() => DotNet.createJSObjectReference("string")).toThrow();
+        expect(() => DotNet.createJSObjectReference(123)).toThrow();
+        expect(() => DotNet.createJSObjectReference(true)).toThrow();
+    });
 });

src/JSInterop/Microsoft.JSInterop/src/Infrastructure/JSObjectReferenceJsonConverter.cs

@@ -22,6 +22,12 @@ public override bool CanConvert(Type typeToConvert)
     public override IJSObjectReference? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
     {
         var id = JSObjectReferenceJsonWorker.ReadJSObjectReferenceIdentifier(ref reader);
+
+        if (id == -1)
+        {
+            return null;
+        }
+
         return new JSObjectReference(_jsRuntime, id);
     }
 

src/JSInterop/Microsoft.JSInterop/test/Infrastructure/JSObjectReferenceJsonConverterTest.cs

@@ -87,4 +87,17 @@ public void Write_WritesValidJson()
         // Assert
         Assert.Equal($"{{\"__jsObjectId\":{jsObjectRef.Id}}}", json);
     }
+
+    [Fact]
+    public void Read_ReturnsNull_WhenJSObjectIdIsMinusOne()
+    {
+        // Arrange
+        var json = "{\"__jsObjectId\":-1}";
+
+        // Act
+        var deserialized = JsonSerializer.Deserialize<IJSObjectReference>(json, JsonSerializerOptions);
+
+        // Assert
+        Assert.Null(deserialized);
+    }
 }