42 lines
1.2 KiB
TypeScript
42 lines
1.2 KiB
TypeScript
import { PageElement } from '../page-element';
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import { generate } from './up-arrow-button.html';
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export class UpArrowButton extends PageElement {
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private static readonly defaultTimeToLive = 2000;
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private static readonly interval = 50;
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private timeToLive = 0;
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public constructor(private scrollTarget: PageElement, label: string) {
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super(generate(label));
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this.htmlRoot.addEventListener('click', this.scrollToTop.bind(this));
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setInterval(() => {
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this.timeToLive = Math.max(0, this.timeToLive - UpArrowButton.interval);
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if (this.timeToLive == 0) {
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this.htmlRoot.style.opacity = '0';
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this.htmlRoot.style.visibility = 'hidden';
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}
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}, UpArrowButton.interval);
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}
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protected initialize() {
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this.scrollTarget.htmlRoot.addEventListener('scroll', () => {
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this.timeToLive = UpArrowButton.defaultTimeToLive;
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this.htmlRoot.style.opacity = '1';
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this.htmlRoot.style.visibility = 'visible';
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if (this.scrollTarget.htmlRoot.scrollTop == 0) {
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this.timeToLive = 0;
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}
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});
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}
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private scrollToTop(e: MouseEvent) {
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if (this.timeToLive > 0) {
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this.scrollTarget.htmlRoot.scrollTo({ top: 0, left: 0, behavior: 'smooth' });
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} else {
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e.preventDefault();
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}
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}
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}
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