@polymer/polymer/lib/utils/flattened-nodes-observer.d.ts

The Polymer library makes it easy to create your own web components. Give your element some markup and properties, and then use it on a site. Polymer provides features like dynamic templates and data binding to reduce the amount of boilerplate you need to

// tslint:disable:variable-name Describing an API that's defined elsewhere.
// tslint:disable:no-any describes the API as best we are able today

import {calculateSplices} from './array-splice.js';

import {microTask} from './async.js';

export {FlattenedNodesObserver};

/**
 * Class that listens for changes (additions or removals) to
 * "flattened nodes" on a given `node`. The list of flattened nodes consists
 * of a node's children and, for any children that are `<slot>` elements,
 * the expanded flattened list of `assignedNodes`.
 * For example, if the observed node has children `<a></a><slot></slot><b></b>`
 * and the `<slot>` has one `<div>` assigned to it, then the flattened
 * nodes list is `<a></a><div></div><b></b>`. If the `<slot>` has other
 * `<slot>` elements assigned to it, these are flattened as well.
 *
 * The provided `callback` is called whenever any change to this list
 * of flattened nodes occurs, where an addition or removal of a node is
 * considered a change. The `callback` is called with one argument, an object
 * containing an array of any `addedNodes` and `removedNodes`.
 *
 * Note: the callback is called asynchronous to any changes
 * at a microtask checkpoint. This is because observation is performed using
 * `MutationObserver` and the `<slot>` element's `slotchange` event which
 * are asynchronous.
 *
 * An example:
 * ```js
 * class TestSelfObserve extends PolymerElement {
 *   static get is() { return 'test-self-observe';}
 *   connectedCallback() {
 *     super.connectedCallback();
 *     this._observer = new FlattenedNodesObserver(this, (info) => {
 *       this.info = info;
 *     });
 *   }
 *   disconnectedCallback() {
 *     super.disconnectedCallback();
 *     this._observer.disconnect();
 *   }
 * }
 * customElements.define(TestSelfObserve.is, TestSelfObserve);
 * ```
 */
declare class FlattenedNodesObserver {

  /**
   * eslint-disable-next-line
   */
  constructor(target: any, callback: any);

  /**
   * eslint-disable-next-line
   */
  static getFlattenedNodes(node: any): any;

  /**
   * Activates an observer. This method is automatically called when
   * a `FlattenedNodesObserver` is created. It should only be called to
   * re-activate an observer that has been deactivated via the `disconnect` method.
   */
  connect(): void;

  /**
   * Deactivates the flattened nodes observer. After calling this method
   * the observer callback will not be called when changes to flattened nodes
   * occur. The `connect` method may be subsequently called to reactivate
   * the observer.
   */
  disconnect(): void;

  /**
   * Flushes the observer causing any pending changes to be immediately
   * delivered the observer callback. By default these changes are delivered
   * asynchronously at the next microtask checkpoint.
   *
   * @returns Returns true if any pending changes caused the observer
   * callback to run.
   */
  flush(): boolean;
}