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The `IJSObjectReference.Invoke` implementation does not support Javascript properties (i.e. getters and setters)

See original GitHub issue

Describe the bug

The IJSObjectReference.Invoke implementation does not support javascript properties (i.e. getters and setters). Since properties are simply encapsulated functions, I think we should be able to read properties with IJSObjectReference.Invoke<PropertyType>("propertyName") and write properties with IJSObjectReference.InvokeVoid("propertyName", value);

To Reproduce

@inject IJSRuntime JS

<button class="btn btn-primary" @onclick="GetLocation">Get Location</button>

<div>@_location</div>

@code {
    string _location;

    private void GetLocation()
    {
        _location = _window.Invoke<string>("location"); // Error here
    }

    IJSInProcessObjectReference _window;

    protected override void OnAfterRender(bool firstRender)
    {
        base.OnAfterRender(firstRender);

        if (firstRender)
        {
            _window = ((IJSInProcessRuntime)JS).Invoke<IJSInProcessObjectReference>("interop.getWindow");
        }
    }
}

Exceptions (if any)

blazor.webassembly.js:1 crit: Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
      Unhandled exception rendering component: The value 'location' is not a function.
      Error: The value 'location' is not a function.
          at e.findFunction (http://localhost:21659/_framework/blazor.webassembly.js:1:1442)
          at b (http://localhost:21659/_framework/blazor.webassembly.js:1:2989)
          at Object.invokeJSFromDotNet (http://localhost:21659/_framework/blazor.webassembly.js:1:3790)
          at Object.w [as invokeJSFromDotNet] (http://localhost:21659/_framework/blazor.webassembly.js:1:60466)
          at _mono_wasm_invoke_js_blazor (http://localhost:21659/_framework/dotnet.5.0.0-rc.1.20431.14.js:1:183003)
          at do_icall (<anonymous>:wasm-function[10583]:0x1944fd)
          at do_icall_wrapper (<anonymous>:wasm-function[3296]:0x79894)
          at interp_exec_method (<anonymous>:wasm-function[2147]:0x4442c)
          at interp_runtime_invoke (<anonymous>:wasm-function[7851]:0x12e8ab)
          at mono_jit_runtime_invoke (<anonymous>:wasm-function[7334]:0x118342)
Microsoft.JSInterop.JSException: The value 'location' is not a function.
Error: The value 'location' is not a function.
    at e.findFunction (http://localhost:21659/_framework/blazor.webassembly.js:1:1442)
    at b (http://localhost:21659/_framework/blazor.webassembly.js:1:2989)
    at Object.invokeJSFromDotNet (http://localhost:21659/_framework/blazor.webassembly.js:1:3790)
    at Object.w [as invokeJSFromDotNet] (http://localhost:21659/_framework/blazor.webassembly.js:1:60466)
    at _mono_wasm_invoke_js_blazor (http://localhost:21659/_framework/dotnet.5.0.0-rc.1.20431.14.js:1:183003)
    at do_icall (<anonymous>:wasm-function[10583]:0x1944fd)
    at do_icall_wrapper (<anonymous>:wasm-function[3296]:0x79894)
    at interp_exec_method (<anonymous>:wasm-function[2147]:0x4442c)
    at interp_runtime_invoke (<anonymous>:wasm-function[7851]:0x12e8ab)
    at mono_jit_runtime_invoke (<anonymous>:wasm-function[7334]:0x118342)
   at Microsoft.JSInterop.WebAssembly.WebAssemblyJSRuntime.InvokeJS(String identifier, String argsJson, JSCallResultType resultType, Int64 targetInstanceId)
   at Microsoft.JSInterop.JSInProcessRuntime.Invoke[String](String identifier, Int64 targetInstanceId, Object[] args)
   at Microsoft.JSInterop.Implementation.JSInProcessObjectReference.Invoke[String](String identifier, Object[] args)
   at Test.Pages.Counter.GetLocation() in C:\Users\Mike\Desktop\Test\Test\Pages\Counter.razor:line 14
   at Microsoft.AspNetCore.Components.EventCallbackWorkItem.InvokeAsync[Object](MulticastDelegate delegate, Object arg)
   at Microsoft.AspNetCore.Components.EventCallbackWorkItem.InvokeAsync(Object arg)
   at Microsoft.AspNetCore.Components.ComponentBase.Microsoft.AspNetCore.Components.IHandleEvent.HandleEventAsync(EventCallbackWorkItem callback, Object arg)
   at Microsoft.AspNetCore.Components.EventCallback.InvokeAsync(Object arg)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.DispatchEventAsync(UInt64 eventHandlerId, EventFieldInfo fieldInfo, EventArgs eventArgs)

Further technical details

dotnet --version
5.0.100-rc.2.20454.3

dotnet --info
.NET SDK (reflecting any global.json):
 Version:   5.0.100-rc.2.20454.3
 Commit:    1e40c01301

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19041
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\5.0.100-rc.2.20454.3\

Host (useful for support):
  Version: 5.0.0-rc.1.20431.14
  Commit:  3bcbbd5b74

.NET SDKs installed:
  2.1.302 [C:\Program Files\dotnet\sdk]
  2.1.401 [C:\Program Files\dotnet\sdk]
  2.1.402 [C:\Program Files\dotnet\sdk]
  2.1.403 [C:\Program Files\dotnet\sdk]
  2.1.503 [C:\Program Files\dotnet\sdk]
  2.1.602 [C:\Program Files\dotnet\sdk]
  2.1.604 [C:\Program Files\dotnet\sdk]
  2.1.801 [C:\Program Files\dotnet\sdk]
  3.0.100-preview9-014004 [C:\Program Files\dotnet\sdk]
  3.0.100 [C:\Program Files\dotnet\sdk]
  3.1.200 [C:\Program Files\dotnet\sdk]
  3.1.302 [C:\Program Files\dotnet\sdk]
  5.0.100-preview.8.20417.9 [C:\Program Files\dotnet\sdk]
  5.0.100-rc.1.20454.5 [C:\Program Files\dotnet\sdk]
  5.0.100-rc.2.20454.3 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-preview9.19424.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0-preview.8.20414.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0-rc.1.20451.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview9-19423-09 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0-preview.8.20407.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0-rc.1.20431.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.0.0-preview9-19423-09 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.0-preview.8.20411.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.0-rc.1.20431.13 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Issue Analytics

State:
Created 3 years ago
Reactions:5
Comments:5 (3 by maintainers)

Top GitHub Comments

2reactions

user72356commented, Sep 16, 2021

I’ve hit that same issue recently while wrapping a JS lib in Blazor. I have a workaround, it’s an ugly hack but that is all we have at the moment…

Add these to your .js file, it will change the prototype for the Object type in JS, akin to extensions methods in C#. It’s apparently not recommended due to potential performance issues since we’re changing objects mid-way through the execution. Any JS engine optimizations that expect a certain object shape could be affected by that.

Object.defineProperty(Object.prototype, "getProperty",
{
    value: function getProperty(key)
    {
        return this[key];
    },
    writable: true,
    configurable: true
});

Object.defineProperty(Object.prototype, "setProperty",
{
    value: function setProperty(key, value)
    {
        this[key] = value;
    },
    writable: true,
    configurable: true
});

Now you can invoke getProperty and setProperty from the .Net side.

public string Target
{
    get => jsRef.Invoke<string>("getProperty", "target");
}

0reactions

danroth27commented, Oct 13, 2022

Closing, as this is being tracked as part of #31151

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