Route Parameters in ASP.NET Core Blazor

@page "/RouteParameter/{text}"

<h1>Blazor is @Text!</h1>

@code {
    [Parameter]
    public string? Text { get; set; }
}

Optional parameters

@page "/RouteParameter/{text?}"

<h1>Blazor is @Text!</h1>

@code {
    [Parameter]
    public string? Text { get; set; }

    protected override void OnInitialized()
    {
        Text = Text ?? "fantastic";
    }
}

Permit app navigation to the same component with a different optional parameter value

protected override void OnParametersSet()
{
    Text = Text ?? "fantastic";
}

References
https://docs.microsoft.com/en-us/aspnet/core/blazor/fundamentals/routing#route-parameters
https://docs.microsoft.com/en-us/aspnet/core/blazor/components/#route-parameters
https://blazor-university.com/routing/route-parameters/
https://blazor-university.com/routing/optional-route-parameters/