Blazor tab example

Index.cshtml

@page "/"

<TabSet>
    <Tab Title="First tab">
        <h4>First tab</h4>
        This is the first tab.
    </Tab>

    @if (showSecondTab)
    {
        <Tab Title="Second">
            <h4>Second tab</h4>
            You can toggle me.
        </Tab>
    }

    <Tab Title="Third">
        <h4>Third tab</h4>

        <label>
            <input type="checkbox" bind=@showSecondTab />
            Toggle second tab
        </label>
    </Tab>
</TabSet>

@functions
{
    bool showSecondTab;
}

ITab.cs

using Microsoft.AspNetCore.Blazor;

public interface ITab
{
    RenderFragment ChildContent { get; }
}

Tab.cshtml

@implements IDisposable
@implements ITab

<li>
    <a onclick=@Activate class="nav-link @TitleCssClass" href="">
        @Title
    </a>
</li>

@functions {
    [CascadingParameter] TabSet ContainerTabSet { get; set; }
    [Parameter] string Title { get; set; }
    [Parameter] public RenderFragment ChildContent { get; private set; }

    string TitleCssClass => ContainerTabSet.ActiveTab == this ? "active" : null;

    protected override void OnInit()
    {
        ContainerTabSet.AddTab(this);
    }

    public void Dispose()
    {
        ContainerTabSet.RemoveTab(this);
    }

    void Activate()
    {
        ContainerTabSet.SetActivateTab(this);
    }
}

tabs.css

.nav-tabs .nav-link {
  border-color: #dee2e6 #dee2e6 #fff;
  border-bottom-color: #dee2e6;
  background-color: #f9f9f9;
}

.nav-tabs .active {
  border-top: 4px solid #e0108b !important;
  padding-top: 5px;
  border-bottom: 1px solid transparent;
  background-color: white;
}

.nav-tabs > li {
  margin-bottom: -1px;
}

.nav-tabs-body {
  border: 1px solid #dee2e6;
  border-top-width: 0;
}

TabSet.cshtml

<!-- Display the tab headers -->
<CascadingValue Value=this>
    <ul class="nav nav-tabs">
        @ChildContent
    </ul>
</CascadingValue>

<!-- Display body for only the active tab -->
<div class="nav-tabs-body p-4">
    @ActiveTab?.ChildContent
</div>

@functions {
    [Parameter] RenderFragment ChildContent { get; set; }

    public ITab ActiveTab { get; private set; }

    public void AddTab(ITab tab)
    {
        if (ActiveTab == null)
        {
            SetActivateTab(tab);
        }
    }

    public void RemoveTab(ITab tab)
    {
        if (ActiveTab == tab)
        {
            SetActivateTab(null);
        }
    }

    public void SetActivateTab(ITab tab)
    {
        if (ActiveTab != tab)
        {
            ActiveTab = tab;
            StateHasChanged();
        }
    }
}

The top level where you use the TabSet will be the only routable component, the ChildContent of the tab set are the individual tabs, and the ChildContent of the tabs are your controls. Here's a simple example of how I'm using the code.

@page "/control"
@using Microsoft.AspNetCore.Components.Authorization
@using LocalDataAccessLibrary
@using UI.Shared.Tabs 

@inject AuthenticationStateProvider AuthenticationStateProvider
@inject UserData _userData


<AuthorizeView>
    <Authorized>
        <h3>Control</h3>
            <TabSet>
                @if (_roles != null && _roles.Contains("Admin"))
                {
                    <Tab Title="Users">
                        <UsersControl />
                    </Tab>
                    <Tab Title="Global">
                        <GlobalControl />
                    </Tab>
                }
                @if (_roles != null && _roles.Contains("Manager"))
                {
                    <Tab Title="Teams">
                        <TeamsControl UserName="@_userName" />
                    </Tab>
                }
                <Tab Title="Profile">
                    <ProfileControl />
                </Tab>
            </TabSet>
    </Authorized>
    <NotAuthorized>
        <p>Please <a href="Identity/Account/Login">Log in</a> to continue</p>
    </NotAuthorized>
</AuthorizeView>

@code {

  private List<string> _roles;
  private string _userName;

  protected override async Task OnInitializedAsync() {
    var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
    var user = authState.User;
    _userName = user.Identity.Name;

    if (user.Identity.IsAuthenticated) {
      _roles = await _userData.GetUsersRolesAsync(_userName);
    }
    else {
      _roles = new List<string>();
    }
  }
}

I was thinking... can you use AJAX or J-Query in a Blazor Page?... AJAX has a tabbed control.