Generic tab button with a text label
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Demo: By default, Tabs creates a TabButton for each tab panel


This component is intended to show a text label, and styled by default to look like a classic tab. Tabs uses this class as the default proxy for tab panels — for each tab panel, Tabs will create a corresponding TabButton.

The button supports a position property that controls whether the tab should style itself appropriately for appearing at the top, bottom, left or right edge of the panels it controls. Visually, the tab button will have no interior border on the edge it shares with the panels, so that the tab button and panel appear to exist on the same surface. By default, the two corners opposite that edge are rounded in skeumorphic reference to the real-world tabs on cardstock folders.

The TabButton class is registered as element <elix-tab-button>.

See also

Basic tabs structure for navigation and configuration
Strip of tab buttons


Ancestry: TabButton → WrappedStandardElementReactiveElement → HTMLElement

Built with mixins AttributeMarshallingMixin, FocusVisibleMixin, LanguageDirectionMixin, ReactiveMixin, RenderUpdatesMixin, ShadowTemplateMixin, and SlotContentMixin.

This element is used to fill a role in Tabs.

$ 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

defaultState property

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

Type: object

Defined by ReactiveMixin

inner property

Returns a reference to the inner standard HTML element.

Type: Element

Defined by WrappedStandardElement

position property

The position of the tab strip with respect to the associated tab panels.

Setting this property does not actually change the tab buttons's position in the document, but lets the tab button know how it should display itself. The standard apperance of TabButton is to hide the visible border between the tab button and its associated panel, and position is used to determine which edge's border should be hidden.

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

Default: 'top'

refineState(state) method

Apply changes to a proposed new state for the component to enforce necessary consistency between state members. See Refining state for details.


  • state: objecta proposed new state for the component

Returns: boolean - true if the state is already acceptable as it is

Defined by ReactiveMixin

render() method

Render the component 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

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.


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

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

Defined by ReactiveMixin

shouldComponentUpdate(nextState) method

Return true if the component should update.

The default implementation does a shallow check of property values like React's PureComponent. This seems adequate for most web components. You can override this to always return true (like React's base Component class), or to perform more specific, deeper checks for changes in state.


  • nextState: objectthe proposed new state for the element

Returns: boolean - true if the component should update (rerender)

Defined by ReactiveMixin

state property

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

Type: object

Defined by ReactiveMixin

suppressFocusVisibility() method

Temporarily suppress visibility of the keyboard focus until the next keydown event.

This can be useful in components like Menu that actively manage where the focus is in response to mouse hover activity. If the user uses the keyboard to invoke a menu, then changes to using the mouse, it can be distracting to see the focus indicator moving as well. In such situations, the component can invoke this method (e.g., in response to mousemove) to temporarily suppress focus visibility.

Defined by FocusVisibleMixin

symbols.contentSlot property

Defined by SlotContentMixin

symbols.rightToLeft property

Type: boolean

Defined by LanguageDirectionMixin

tabAlign property

The alignment of the tabs within the tab strip.

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

Default: 'start'

template property

The template copied into the shadow tree of new instances of this element.

The default value of this property is a template that includes an instance the standard element being wrapped, with a <slot> element inside that to pick up the element's light DOM content. For example, if you wrap an <a> element, then the default template will look like:

  :host {
    display: inline-block;
  <a id="inner">

The display styling applied to the host will be block for elements that are block elements by default, and inline-block (not inline) for other elements.

If you'd like the template to include other elements, then override this property and return a template of your own. The template should include an instance of the standard HTML element you are wrapping, and the ID of that element should be "inner".

Type: string|HTMLTemplateElement

Defined by WrappedStandardElement

updates property

The attributes and properies that should be applied to the component on render. By default, this is an empty plain object. Your mixin or component can extend this to identify the properties to set on the host element or elements in the shadow subtree.

Type: object

Defined by RenderUpdatesMixin

wrap(extendsTag) static method

Creates a class that wraps a standard HTML element.

Note that the resulting class is a subclass of WrappedStandardElement, not the standard class being wrapped. E.g., if you call WrappedStandardElement.wrap('a'), you will get a class whose shadow tree will include an anchor element, but the class will not inherit from HTMLAnchorElement.


  • extendsTag: stringthe standard HTML element tag to extend

Defined by WrappedStandardElement