Mixin which allows a component to delegate its own selection semantics to a target element.
This is useful when defining components that act as optional features for a component that acts like a list. See basic-arrow-selection and basic-page-dots for examples of components used as optional features for components like basic-carousel. A typical usage might be:
<basic-arrow-selection>
<basic-carousel>
... images, etc. ...
</basic-carousel>
</basic-arrow-selection>
Because basic-arrow-selection uses the
TargetSelection mixin, it exposes members to access a
selection: selectNext, selectPrevious, selectedIndex, etc. These are
all delegated to the child component (here, a basic-carousel).
This mixin expects a target property to be set to the element actually
managing the selection. You can set that property yourself, or you can use
the ContentFirstChildTarget mixin to
implicitly take the component's first child as the target. This is what
basic-arrow-selection (above) does.
Kind: global class
- TargetSelection
- .items :
Array.<HTMLElement> - .itemsChanged()
- .selectedIndex :
number - .selectedItem :
HTMLElement - .target :
HTMLElement
- .items :
The current set of items in the list.
Kind: instance property of TargetSelection
This method is invoked when the underlying contents change. It is also invoked on component initialization – since the items have "changed" from being nothing.
Kind: instance method of TargetSelection
The index of the item which is currently selected, or -1 if there is no selection.
Kind: instance property of TargetSelection
The currently selected item, or null if there is no selection.
Kind: instance property of TargetSelection
Gets/sets the target element to which this component will delegate selection actions.
Kind: instance property of TargetSelection