The Mix manifest does not exist.

I am working to make a chat system for my website. Now I am getting this error. My front-end code:

{{ config('app.name', 'Laravel') }} {{ config('app.name', 'Laravel') }}

            <div class="collapse navbar-collapse" id="navbarSupportedContent">
                
                <ul class="navbar-nav mr-auto">

                </ul>

               
                <ul class="navbar-nav ml-auto">
                    @guest
                        <li class="nav-item">
                            <a class="nav-link" href="{{ route('login') }}">{{ __('Login') }}</a>
                        </li>
                        @if (Route::has('register'))
                            <li class="nav-item">
                                <a class="nav-link" href="{{ route('register') }}">{{ __('Register') }}</a>
                            </li>
                        @endif
                    @else
                        <li class="nav-item dropdown">
                            <a id="navbarDropdown" class="nav-link dropdown-toggle" href="#" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false" v-pre>
                                {{ Auth::user()->name }} <span class="caret"></span>
                            </a>

                            <div class="dropdown-menu dropdown-menu-right" aria-labelledby="navbarDropdown">
                                <a class="dropdown-item" href="{{ route('logout') }}"
                                   onclick="event.preventDefault();
                                                 document.getElementById('logout-form').submit();">
                                    {{ __('Logout') }}
                                </a>

                                <form id="logout-form" action="{{ route('logout') }}" method="POST" style="display: none;">
                                    @csrf
                                </form>
                            </div>
                        </li>
                    @endguest
                </ul>
            </div>
        </div>
    </nav>

    <main class="py-4">
        @yield('content')
    </main>
</div>
   
<script src="{{ mix('js/app.js') }}" defer></script>