Dialog

A basic type of overlay that presents its assigned children as a basic modal dialog which appears on top of the main page content. The user must interact with the dialog before they can return to the page.

Tap/click here or press Esc to cancel.

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Demo: Clicking the button opens a simple dialog

Dialog uses ModalBackdrop to add a backdrop behind the main overlay content.

Usage

import Dialog from 'elix/src/Dialog.js';
const dialog = new Dialog(); // or
const dialog = document.createElement('elix-dialog');

In HTML:

<script type="module" src="node_modules/elix/src/Dialog.js"></script>
<elix-dialog>
  <!-- Dialog contents go here -->
</elix-dialog>

As with other elements that use DialogModalityMixin, use modal overlays only when it's critical that you gain the user's attention, or when you need them to provide a response in order to continue. For all other overlay situations, consider using a Popup or other component using PopupModalityMixin.

For a simple form of Dialog that can be easily created in JavaScript to ask a single question, see AlertDialog.

Keyboard support

Dialog uses FocusCaptureMixin to wrap the keyboard focus within the dialog. The keyboard focus is initially on the dialog itself. Pressing Tab will cycle through the dialog's focusable elements. When the user reaches the last of the dialog's focusable elements, pressing Tab focuses the dialog again, repeating the cycle.

Pressing the Esc key closes the dialog.

API

$ property

The collection of references to the elements with IDs 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.

Such references simplify a component's access to its own elements. In exchange, this mixin trades off a one-time cost of querying all elements in the shadow tree instead of paying an ongoing cost to query for an element each time the component wants to inspect or manipulate it.

These shadow element references are established the first time you read the $ property. They are * not updated if you subsequently modify the shadow tree yourself (to replace one item with another, to add new items with id attributes, etc.).

Type: object

Defined by ShadowTemplateMixin inherited from ElementBase

close(result) method

Close the component (if not already closed).

Some components like AlertDialog want to indicate why or how they were closed. To support such scenarios, you can supply a value to the optional result parameter. This result will be made available in the whenClosed promise and the state.result member.

Parameters:
  • result: objectan indication of how or why the element closed

Defined by OpenCloseMixin

closed property

True if the element is currently closed.

Type: boolean

Defined by OpenCloseMixin

closeFinished property

True if the element has completely closed.

For components not using asynchronous open/close effects, this property returns the same value as the closed property. For elements that have a true value of state.openCloseEffects (e.g., elements using TransitionEffectMixin), this property returns true only if state.effect is "close" and state.effectPhase is "after".

Type: boolean

Defined by OpenCloseMixin

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 inherited from ElementBase

open() method

Open the element (if not already opened).

Defined by OpenCloseMixin

opened property

True if the element is currently closed.

Type: boolean

Defined by OpenCloseMixin

opened-changed event

Raised when the opened/closed state of the component changes.

Defined by OpenCloseMixin

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 inherited from ElementBase

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.

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

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

Defined by ReactiveMixin inherited from ElementBase

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.

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

Parameters:
  • nextState: objectthe proposed new state for the element

Defined by ReactiveMixin inherited from ElementBase

state property

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

Type: object

Defined by ReactiveMixin inherited from ElementBase

symbols.keydown() method

See the symbols documentation for details.

Defined by KeyboardMixin

toggle(opened) method

Toggle the open/close state of the element.

Parameters:
  • opened: booleantrue if the element should be opened, false if closed.

Defined by OpenCloseMixin

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 inherited from ElementBase

whenClosed() method

This method can be used as an alternative to listening to the "opened-changed" event, particularly in situations where you want to only handle the next time the component is closed.

Returns: Promise A promise that resolves when the element has completely closed, including the completion of any asynchronous opening effect.

Defined by OpenCloseMixin

wrap(template) static method

Wrap a base template with elements necessary to capture focus.

Call this method in a components symbols.template property.

Note: The wrap method hangs off of FocusCaptureMixin like a static method; the mixin does not add it to an element's prototype chain. Accordingly, you must invoke this method as FocusCaptureMixin.wrap(template), not this.wrap(template).

Returns: string a template that includes left/right arrow buttons

Parameters:
  • template: stringfor the element(s) controlled by the arrow buttons

Defined by FocusCaptureMixin

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