1aebf165db
The `ViewportScroller` figures out which element to scroll into view using `document.getElementById`. The problem is that it won't find elements inside the shadow DOM. These changes add some extra logic that goes through all the shadow roots to look for the element. Fixes #41470. PR Close #41644
280 lines
8.8 KiB
TypeScript
280 lines
8.8 KiB
TypeScript
/**
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* @license
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* Copyright Google LLC All Rights Reserved.
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*
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* Use of this source code is governed by an MIT-style license that can be
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* found in the LICENSE file at https://angular.io/license
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*/
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import {ɵɵdefineInjectable, ɵɵinject} from '@angular/core';
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import {DOCUMENT} from './dom_tokens';
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/**
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* Defines a scroll position manager. Implemented by `BrowserViewportScroller`.
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*
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* @publicApi
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*/
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export abstract class ViewportScroller {
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// De-sugared tree-shakable injection
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// See #23917
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/** @nocollapse */
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static ɵprov = /** @pureOrBreakMyCode */ ɵɵdefineInjectable({
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token: ViewportScroller,
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providedIn: 'root',
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factory: () => new BrowserViewportScroller(ɵɵinject(DOCUMENT), window)
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});
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/**
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* Configures the top offset used when scrolling to an anchor.
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* @param offset A position in screen coordinates (a tuple with x and y values)
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* or a function that returns the top offset position.
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*
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*/
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abstract setOffset(offset: [number, number]|(() => [number, number])): void;
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/**
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* Retrieves the current scroll position.
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* @returns A position in screen coordinates (a tuple with x and y values).
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*/
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abstract getScrollPosition(): [number, number];
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/**
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* Scrolls to a specified position.
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* @param position A position in screen coordinates (a tuple with x and y values).
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*/
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abstract scrollToPosition(position: [number, number]): void;
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/**
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* Scrolls to an anchor element.
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* @param anchor The ID of the anchor element.
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*/
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abstract scrollToAnchor(anchor: string): void;
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/**
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* Disables automatic scroll restoration provided by the browser.
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* See also [window.history.scrollRestoration
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* info](https://developers.google.com/web/updates/2015/09/history-api-scroll-restoration).
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*/
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abstract setHistoryScrollRestoration(scrollRestoration: 'auto'|'manual'): void;
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}
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/**
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* Manages the scroll position for a browser window.
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*/
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export class BrowserViewportScroller implements ViewportScroller {
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private offset: () => [number, number] = () => [0, 0];
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constructor(private document: Document, private window: Window) {}
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/**
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* Configures the top offset used when scrolling to an anchor.
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* @param offset A position in screen coordinates (a tuple with x and y values)
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* or a function that returns the top offset position.
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*
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*/
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setOffset(offset: [number, number]|(() => [number, number])): void {
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if (Array.isArray(offset)) {
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this.offset = () => offset;
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} else {
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this.offset = offset;
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}
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}
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/**
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* Retrieves the current scroll position.
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* @returns The position in screen coordinates.
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*/
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getScrollPosition(): [number, number] {
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if (this.supportsScrolling()) {
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return [this.window.pageXOffset, this.window.pageYOffset];
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} else {
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return [0, 0];
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}
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}
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/**
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* Sets the scroll position.
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* @param position The new position in screen coordinates.
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*/
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scrollToPosition(position: [number, number]): void {
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if (this.supportsScrolling()) {
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this.window.scrollTo(position[0], position[1]);
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}
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}
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/**
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* Scrolls to an element and attempts to focus the element.
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*
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* Note that the function name here is misleading in that the target string may be an ID for a
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* non-anchor element.
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*
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* @param target The ID of an element or name of the anchor.
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*
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* @see https://html.spec.whatwg.org/#the-indicated-part-of-the-document
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* @see https://html.spec.whatwg.org/#scroll-to-fragid
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*/
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scrollToAnchor(target: string): void {
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if (!this.supportsScrolling()) {
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return;
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}
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// TODO(atscott): The correct behavior for `getElementsByName` would be to also verify that the
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// element is an anchor. However, this could be considered a breaking change and should be
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// done in a major version.
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const elSelected = findAnchorFromDocument(this.document, target);
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if (elSelected) {
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this.scrollToElement(elSelected);
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// After scrolling to the element, the spec dictates that we follow the focus steps for the
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// target. Rather than following the robust steps, simply attempt focus.
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this.attemptFocus(elSelected);
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}
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}
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/**
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* Disables automatic scroll restoration provided by the browser.
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*/
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setHistoryScrollRestoration(scrollRestoration: 'auto'|'manual'): void {
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if (this.supportScrollRestoration()) {
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const history = this.window.history;
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if (history && history.scrollRestoration) {
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history.scrollRestoration = scrollRestoration;
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}
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}
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}
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/**
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* Scrolls to an element using the native offset and the specified offset set on this scroller.
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*
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* The offset can be used when we know that there is a floating header and scrolling naively to an
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* element (ex: `scrollIntoView`) leaves the element hidden behind the floating header.
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*/
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private scrollToElement(el: HTMLElement): void {
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const rect = el.getBoundingClientRect();
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const left = rect.left + this.window.pageXOffset;
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const top = rect.top + this.window.pageYOffset;
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const offset = this.offset();
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this.window.scrollTo(left - offset[0], top - offset[1]);
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}
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/**
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* Calls `focus` on the `focusTarget` and returns `true` if the element was focused successfully.
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*
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* If `false`, further steps may be necessary to determine a valid substitute to be focused
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* instead.
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*
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* @see https://html.spec.whatwg.org/#get-the-focusable-area
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* @see https://developer.mozilla.org/en-US/docs/Web/API/HTMLOrForeignElement/focus
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* @see https://html.spec.whatwg.org/#focusable-area
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*/
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private attemptFocus(focusTarget: HTMLElement): boolean {
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focusTarget.focus();
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return this.document.activeElement === focusTarget;
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}
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/**
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* We only support scroll restoration when we can get a hold of window.
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* This means that we do not support this behavior when running in a web worker.
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*
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* Lifting this restriction right now would require more changes in the dom adapter.
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* Since webworkers aren't widely used, we will lift it once RouterScroller is
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* battle-tested.
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*/
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private supportScrollRestoration(): boolean {
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try {
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if (!this.supportsScrolling()) {
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return false;
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}
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// The `scrollRestoration` property could be on the `history` instance or its prototype.
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const scrollRestorationDescriptor = getScrollRestorationProperty(this.window.history) ||
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getScrollRestorationProperty(Object.getPrototypeOf(this.window.history));
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// We can write to the `scrollRestoration` property if it is a writable data field or it has a
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// setter function.
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return !!scrollRestorationDescriptor &&
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!!(scrollRestorationDescriptor.writable || scrollRestorationDescriptor.set);
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} catch {
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return false;
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}
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}
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private supportsScrolling(): boolean {
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try {
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return !!this.window && !!this.window.scrollTo && 'pageXOffset' in this.window;
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} catch {
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return false;
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}
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}
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}
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function getScrollRestorationProperty(obj: any): PropertyDescriptor|undefined {
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return Object.getOwnPropertyDescriptor(obj, 'scrollRestoration');
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}
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function findAnchorFromDocument(document: Document, target: string): HTMLElement|null {
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const documentResult = document.getElementById(target) || document.getElementsByName(target)[0];
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if (documentResult) {
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return documentResult;
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}
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// `getElementById` and `getElementsByName` won't pierce through the shadow DOM so we
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// have to traverse the DOM manually and do the lookup through the shadow roots.
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if (typeof document.createTreeWalker === 'function' && document.body &&
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((document.body as any).createShadowRoot || document.body.attachShadow)) {
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const treeWalker = document.createTreeWalker(document.body, NodeFilter.SHOW_ELEMENT);
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let currentNode = treeWalker.currentNode as HTMLElement | null;
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while (currentNode) {
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const shadowRoot = currentNode.shadowRoot;
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if (shadowRoot) {
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// Note that `ShadowRoot` doesn't support `getElementsByName`
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// so we have to fall back to `querySelector`.
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const result =
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shadowRoot.getElementById(target) || shadowRoot.querySelector(`[name="${target}"]`);
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if (result) {
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return result;
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}
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}
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currentNode = treeWalker.nextNode() as HTMLElement | null;
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}
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}
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return null;
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}
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/**
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* Provides an empty implementation of the viewport scroller.
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*/
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export class NullViewportScroller implements ViewportScroller {
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/**
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* Empty implementation
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*/
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setOffset(offset: [number, number]|(() => [number, number])): void {}
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/**
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* Empty implementation
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*/
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getScrollPosition(): [number, number] {
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return [0, 0];
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}
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/**
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* Empty implementation
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*/
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scrollToPosition(position: [number, number]): void {}
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/**
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* Empty implementation
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*/
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scrollToAnchor(anchor: string): void {}
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/**
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* Empty implementation
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*/
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setHistoryScrollRestoration(scrollRestoration: 'auto'|'manual'): void {}
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}
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