Tabs

Basic tabs structure for navigation and configuration
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Demo: Tabs element with default tab buttons

Overview

Tabs is a set of tabbed panels that can be navigated by selecting corresponding tab buttons. Tabs builds on Explorer, which takes care of the relative positioning of the tab buttons and the tab panels, and ensures that the selection state of the buttons and panels remains in sync. Tabs itself mostly adds the use of TabButton elements as default proxies for the tab panels (the elements the user can click to select a panel), and TabStrip to contain the list of tab buttons. Tabs also adds accessibility support specific to tabbed interfaces.

A typical example of Tabs being used for navigation, using custom tab buttons:

home
Home
search
Search
settings
Settings
Home page
Search page
Settings page
Demo: Tabs used for navigation

You can select a tab with mouse/touch or a keyboard.

The Tabs class is registered as element <elix-tabs>.

Usage

Use Tabs for situations in which the user can directly control which modal state is presented. Tabs are typically used to allow a UI to offer more controls than can fit in a confined area at a time.

  • A common use case is Settings or configuration UIs. Here the classic look of a tabbed dialog or property sheet is addressed with the Elix's default TabButton elements, although other looks are possible.
  • Tabs may also be used in a main window to downplay less-commonly used aspects of a UI.
  • Tabs are also an extremely common navigation model. Many mobile applications present a navigation toolbar that behave like tabs, presenting 3–5 buttons that correspond to the app's main areas. In navigation use cases, the tab buttons typically have a toolbar button style rather than a classic tabbed appearance.

Using default tab buttons

By default, you only need to provide Tabs with child items that it will use as the tab panels. For best results, give each panel a text lable in an aria-label attribute.

<elix-tabs>
  <div aria-label="One">Page one</div>
  <div aria-label="Two">Page two</div>
  <div aria-label="Three">Page three</div>
</elix-tabs>

For each panel, Tabs will create a TabButton instance, and that panel's aria-label as the content of the tab button. See the first demo above for an example.

Positioning and aligning tab buttons

Tabs exposes proxyListPosition and tabAlign properties that let you control, respectively, how the strip of tabs is positioned with respect to the panels and how they are visually aligned within the strip of tabs.

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Show tabs on:

Align tabs:

Demo: You can customize tab position and alignment

Custom content in default tab buttons

If you would like to use the default tab button appearance, but have more control over the content of the tab buttons, you can create the tab buttons yourself. Add a slot="tabButtons" attribute to each button to specify that you want it to be treated as a tab button:

<elix-tabs>
  <elix-tab-button slot="tabButtons">Un</elix-tab-button>
  <div aria-label="One">Page one</div>

  <elix-tab-button slot="tabButtons">Deux</elix-tab-button>
  <div aria-label="Two">Page two</div>

  <elix-tab-button slot="tabButtons">Trois</elix-tab-button>
  <div aria-label="Three">Page three</div>
</elix-tabs>

Because the <elix-tab-button> instances are HTML elements, you can include arbitrarily complex content inside them: add icons, other graphical elements, etc.

As long as the relative order of the tab buttons and the panel elements are consistent, it doesn't matter where the tab buttons appear. You can interleave them with the panels (above) or, if it's more convenient, group the tab buttons together:

<elix-tabs>
  <elix-tab-button slot="tabButtons">Un</elix-tab-button>
  <elix-tab-button slot="tabButtons">Trois</elix-tab-button>
  <elix-tab-button slot="tabButtons">Deux</elix-tab-button>

  <div aria-label="One">Page one</div>
  <div aria-label="Two">Page two</div>
  <div aria-label="Three">Page three</div>
</elix-tabs>

In either case, the result is:

Un Deux Trois
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Demo: Tabs with custom content in standard tab buttons

Using custom tab buttons

You can also provide your custom elements as the tab buttons. For example, the demo showing tabs used for navigation at the top of this page can be created using code along these lines:

<elix-tabs tab-position="bottom" tab-align="stretch">

  <toolbar-tab slot="tabButtons" aria-label="Home">
    <div class="material-icons">home</div>
    Home
  </toolbar-tab>

  <toolbar-tab slot="tabButtons" aria-label="Search">
    <div class="material-icons">search</div>
    Search
  </toolbar-tab>

  <toolbar-tab slot="tabButtons" aria-label="Settings">
    <div class="material-icons">settings</div>
    Settings
  </toolbar-tab>

  <div>Home page</div>
  <div>Search page</div>
  <div>Settings page</div>

</elix-tabs>

This uses Google's Material Design icons for button icons, but you can use whatever techniques are appropriate for your app's visual design.

Customizing the stage

By default, Tabs uses Modes as the main stage showing the selected tab panel. Modes provides an immediate transition between panels, but you can override the stageTag property to specify another type of stage, such as CrossfadeStage:

Standard rooms

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Demo: CrossfadeStage provides a crossfade effect when switching tabs

The tabbed navigation example at the top of the page shows a SlidingPages element as the stage, which adds a horizontal sliding effect and support for touch/trackpad swipe gestures.

See also

Modes
Shows a single panel at a time
TabButton
Generic tab button with a text label
TabStrip
Strip of tab buttons

API

Ancestry: Tabs → ExplorerReactiveElement → HTMLElement

Built with mixins AttributeMarshallingMixin, GenericMixin, LanguageDirectionMixin, ReactiveMixin, ShadowTemplateMixin, SingleSelectionMixin, and SlotItemsMixin.

By default, this uses these elements in the following roles:

$ property

A convenient shortcut for looking up an element by ID in the component's Shadow DOM subtree.

Example: if component's template contains a shadow element <button id="foo">, you can use the reference this.$.foo to obtain the corresponding button in the component instance's shadow tree. The $ function is simply a shorthand for getElementById, so this.$.foo is the same as this.shadowRoot.getElementById('foo').

Type: object

Defined by ShadowTemplateMixin

canSelectNext property

True if the selection can be moved to the next item, false if not (the selected item is the last item in the list).

Type: boolean

Defined by SingleSelectionMixin

canSelectPrevious property

True if the selection can be moved to the previous item, false if not (the selected item is the first one in the list).

Type: boolean

Defined by SingleSelectionMixin

defaultState property

The default state for the component. This can be extended by mixins and classes to provide additional default state.

Type: State

Defined by ReactiveMixin

items property

The current set of items drawn from the element's current state.

Type: Array.|null

Defined by ContentItemsMixin

items-changed event

Raised when the items property changes.

Defined by ContentItemsMixin

proxies property

The current set of proxy elements that correspond to the component's main items. If you have assigned elements to the proxy slot, this returns the collection of those elements. Otherwise, this will return a collection of default proxies generated by the component, one for each item.

Type: Array.

Defined by Explorer

proxyListOverlap property

True if the list of proxies should overlap the stage, false if not.

Type: boolean

Default: false

Defined by Explorer

proxyListPosition property

The position of the proxy list relative to the stage.

The start and end values refer to text direction: in left-to-right languages such as English, these are equivalent to left and right, respectively.

Type: 'bottom'|'end'|'left'|'right'|'start'|'top'

Default: 'start'

Defined by Explorer

proxyListRole property

The class, tag, or template used to create the Explorer's list of proxies.

Type: (component class constructor)|HTMLTemplateElement|string

Default: ListBox

Defined by Explorer

proxyRole property

The class, tag, or template used to create default proxies for the list items.

Type: (component class constructor)|HTMLTemplateElement|string

Default: 'div'

Defined by Explorer

render() method

Render pending component changes to the DOM.

This method does nothing if the state has not changed since the last render call.

This method invokes all internal render methods. It then invoked componentDidMount (for first render) or componentDidUpdate (for subsequent renders).

Defined by ReactiveMixin

selected-index-changed event

Raised when the selectedIndex property changes.

Defined by SingleSelectionMixin

selectedIndex property

The index of the currently-selected item, or -1 if no item is selected.

Type: number

Defined by SingleSelectionMixin

selectedItem property

The currently-selected item, or null if no item is selected.

Type: Element

Defined by SingleSelectionMixin

selectFirst() method

Select the first item in the list.

Returns: Boolean True if the selection changed, false if not.

Defined by SingleSelectionMixin

selectionRequired property

True if the list should always have a selection (if it has items).

Type: boolean

Default: false

Defined by SingleSelectionMixin

selectionWraps property

True if selection navigations wrap from last to first, and vice versa.

Type: boolean

Default: false

Defined by SingleSelectionMixin

selectLast() method

Select the last item in the list.

Returns: Boolean True if the selection changed, false if not.

Defined by SingleSelectionMixin

selectNext() method

Select the next item in the list.

If the list has no selection, the first item will be selected.

Returns: Boolean True if the selection changed, false if not.

Defined by SingleSelectionMixin

selectPrevious() method

Select the previous item in the list.

If the list has no selection, the last item will be selected.

Returns: Boolean True if the selection changed, false if not.

Defined by SingleSelectionMixin

setState(changes) method

Update the component's state by merging the specified changes on top of the existing state. If the component is connected to the document, and the new state has changed, this returns a promise to asynchronously render the component. Otherwise, this returns a resolved promise.

Parameters:

  • changes: objectthe changes to apply to the element's state

Returns: Promise - resolves when the new state has been rendered

Defined by ReactiveMixin

stageRole property

The class, tag, or template used for the main "stage" element that shows a single item at a time.

Type: (component class constructor)|HTMLTemplateElement|string

Default: Modes

Defined by Explorer

state property

The component's current state. The returned state object is immutable. To update it, invoke setState.

Type: State

Defined by ReactiveMixin

[symbols.contentSlot] property

Defined by SlotContentMixin

[symbols.itemMatchesState](item, state) method

Returns true if the given item should be shown in the indicated state.

Parameters:

  • item: HTMLElement|SVGElement
  • state: PlainObject

Returns: boolean

Defined by ContentItemsMixin

[symbols.render](changed) method

Internal method for rendering any recent changes in state to the DOM.

The default implementation of this method does nothing. Override this method in your component to update your component's host element and any shadow elements to reflect the component's new state. See the rendering example.

Be sure to call super in your method implementation so that your component's base classes and mixins have a chance to perform their own render work.

Parameters:

  • changed: objectdictionary of flags indicating which state members have changed since the last render

Defined by ReactiveMixin

tabAlign property

The alignment of the tabs within the tab strip.

The value of this property will be forwarded to the corresponding property

Type: 'start'|'center'|'end'|'stretch'

Default: 'start'