Winform like keyboard-events with JS event interception with fine-grained preventDefault control directly baked into C# Blazor Server/Webassembly.

[hintsofttech]

if we could do this enterprise level of keyboard navigations, key-level operations, key-prevention for typing everything would be very appreciable or if not possible in anyway it should provide keyboard helper package to accomplish the task.

like suggested by ChatGPT below or better so that developer need not to worry what's going inside js. developer should feel all c# native :-
// wwwroot/keyboardHelper.js

export function initKeyboardHandler(dotNetHelper, options) {
const keysToPrevent = options.keysToPrevent || [];
const keyMappings = options.keyMappings || {};

function getComboKey(e) {
let combo = '';
if (e.ctrlKey) combo += 'Ctrl+';
if (e.shiftKey) combo += 'Shift+';
if (e.altKey) combo += 'Alt+';
combo += e.key.toLowerCase();
return combo;
}

function onKeyDown(e) {
const combo = getComboKey(e);

if (keysToPrevent.some(k => k.toLowerCase() === combo)) {
  e.preventDefault();
  return;
}

const mappedKey = keyMappings[combo] || e.key;
dotNetHelper.invokeMethodAsync('OnKeyAllowed', mappedKey, e.code);

}

window.addEventListener('keydown', onKeyDown);

return {
dispose: () => window.removeEventListener('keydown', onKeyDown)
};
}

KeyboardHelper service
csharp
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using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.JSInterop;

namespace BlazorKeyboardHelper
{
public class KeyboardHelper : IAsyncDisposable
{
private readonly IJSRuntime _js;
private IJSObjectReference _module;
private DotNetObjectReference _objRef;

    public event Func<KeyboardAction, string, Task> OnKeyPressed;

    public KeyboardHelper(IJSRuntime js)
    {
        _js = js;
    }

    public async Task InitializeAsync(IEnumerable<string> keysToPrevent, Dictionary<string, string> keyMappings)
    {
        _module = await _js.InvokeAsync<IJSObjectReference>("import", "./_content/BlazorKeyboardHelper/keyboardHelper.js");
        _objRef = DotNetObjectReference.Create(this);

        var options = new
        {
            keysToPrevent,
            keyMappings
        };

        await _module.InvokeVoidAsync("initKeyboardHandler", _objRef, options);
    }

    [JSInvokable]
    public async Task OnKeyAllowed(string mappedKey, string code)
    {
        if (Enum.TryParse<KeyboardAction>(mappedKey, true, out var action))
        {
            if (OnKeyPressed != null)
                await OnKeyPressed.Invoke(action, code);
        }
        else
        {
            // Optionally handle unmapped keys or ignore
        }
    }

    public async ValueTask DisposeAsync()
    {
        if (_module != null)
        {
            await _module.DisposeAsync();
        }
        _objRef?.Dispose();
    }
}

}

public enum KeyboardAction
{
// Letters
A, B, C, D, E, F, G, H, I, J, K, L, M,
N, O, P, Q, R, S, T, U, V, W, X, Y, Z,

    // Numbers (top row)
    Digit0, Digit1, Digit2, Digit3, Digit4,
    Digit5, Digit6, Digit7, Digit8, Digit9,

    // Numpad keys
    Numpad0, Numpad1, Numpad2, Numpad3, Numpad4,
    Numpad5, Numpad6, Numpad7, Numpad8, Numpad9,
    NumpadMultiply, NumpadAdd, NumpadSubtract,
    NumpadDecimal, NumpadDivide,

    // Function keys
    F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12,

    // Navigation keys
    ArrowUp, ArrowDown, ArrowLeft, ArrowRight,
    Home, End, PageUp, PageDown,

    // Modifiers
    Shift, Control, Alt, Meta, CapsLock,

    // Editing keys
    Backspace, Tab, Enter, Escape, Space,
    Delete, Insert,

    // Other common keys
    ContextMenu, NumLock, ScrollLock, Pause, PrintScreen,

    // Symbols & punctuation (common US layout)
    Minus, Equal, BracketLeft, BracketRight,
    Backslash, Semicolon, Quote, Backquote, Comma, Period, Slash,

    // Media keys (optional)
    MediaPlayPause, MediaStop, MediaNextTrack, MediaPreviousTrack,

    // Additional keys can be added here as needed
}

builder.Services.AddScoped();
protected override async Task OnInitializedAsync()
{
KeyboardHelper.OnKeyPressed += HandleKeyPressed;
}