WebView2

Setup.cs

// WebView2 - My Setup 

internal partial class MainForm : Form
    // [...]
    protected override async void OnLoad(EventArgs e)
    {
        base.OnLoad(e);
        var webView2Environment = await CoreWebView2Environment.CreateAsync();
        await UI.EnsureCoreWebView2Async(webView2Environment);
        UI.CoreWebView2.WebMessageReceived += UI_WebMessageReceived;
        UI.CoreWebView2.Settings.AreHostObjectsAllowed = true;
        UI.CoreWebView2.Settings.AreDefaultContextMenusEnabled = false;
        UI.CoreWebView2.Settings.AreDefaultScriptDialogsEnabled = false;

        UI.CoreWebView2.OpenDevToolsWindow();

        // Load
        //string pageContent = WebRessourceLoader.load();
        UI.CoreWebView2.Navigate("file:///" + Path.GetFullPath("www/index.html").Replace("\\", "/")); // single page

        // load WebMessageHandler
        JsObjectLoader.Load(UI.CoreWebView2);
        LoacWebLayerV1();
    }

    private void UI_WebMessageReceived(object? sender, CoreWebView2WebMessageReceivedEventArgs e)
    {
        var jsonMessage = e.TryGetWebMessageAsString();  // always a JSON string
        if (string.IsNullOrEmpty(jsonMessage))
        {
            return;
        }

        WebMessageManager.WebMessageHandle(jsonMessage);
    }
}
// [...]
internal static class WebMessageManager
{
    private readonly static JsonSerializerOptions s_jsonSerializerOptions = new JsonSerializerOptions
    {
        AllowTrailingCommas = true,
        IncludeFields = true,
    };

    private static IDictionary<string, IWebMessageHandler> _webMessagesHandler = new Dictionary<string, IWebMessageHandler>();
    public static void RegistrateHandler(IWebMessageHandler messageHandler)
    {
        _webMessagesHandler.Add(messageHandler.Action, messageHandler);
    }
    public static void WebMessageHandle(string jsonData)
    {
        WebMessage? message = JsonSerializer.Deserialize<WebMessage>(jsonData, s_jsonSerializerOptions);
        if (message != null && _webMessagesHandler.TryGetValue(message.Action, out IWebMessageHandler? webMessagesHandler))
        {
             webMessagesHandler?.OnAction(message.ID, message.Value);
        }
    }
}

internal sealed class WebMessage
{
    [JsonPropertyName("action")]
    public string Action = null!;

    [JsonPropertyName("id")]
    public string? ID = null;

    [JsonPropertyName("value")]
    public string? Value = null;
}

internal interface IWebMessageHandler
{
    public CoreWebView2 WebView { get; internal init; }
    public string Action { get; internal init; }
    void OnAction(string? id, string? data);

}

internal abstract class WebMessageHandlerBase : IWebMessageHandler
{
    private readonly static JsonSerializerOptions s_jsonSerializerOptions = new JsonSerializerOptions
    {
        AllowTrailingCommas = true,
        IncludeFields = true,
    };

    public string Action { get; init; }
    public CoreWebView2 WebView { get; init; }
    internal WebMessageHandlerBase(CoreWebView2 webView, string actionName)
    {  
        WebView = webView;
        Action = actionName;
    }

    public abstract void OnAction(string? id, string? data);

    public void Respose<T>(string? id, T data)
        where T : class
    {
        WebMessage webMessage = new WebMessage
        {
            Action = Action,
            ID = id,
            Value = JsonSerializer.Serialize(data, s_jsonSerializerOptions)
        };

        string message = JsonSerializer.Serialize(webMessage, s_jsonSerializerOptions);

        WebView.PostWebMessageAsJson(message);
    }
}

/// JS
const webMessageManager = (()=>{ 
    const actions = {};

    window.chrome.webview.addEventListener('message', e => {
        actions[e.data.id](JSON.parse(e.data.value));
        delete actions[e.data.id];
    });

    function sendMessage(action, id, data) {
        var msgObject = {
            action: action,
            id: id,
            value: JSON.stringify(data)
        };

        var json = JSON.stringify(msgObject);
        window.chrome.webview.postMessage(json);
    }

    return {
        sendMessage: (action, data) => { 
            sendMessage(action, null, data);
        },
        postMessage: (action, data) => { 
            var id = crypto.randomUUID();
            console.log(id);
            sendMessage(action, id, data);
            return new Promise((resolve) => {
                actions[id] = resolve; 
            });
        }
    };
})();