69 lines
1.7 KiB
TypeScript
69 lines
1.7 KiB
TypeScript
export default interface NavigationPresenter {
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openHistoryPrev(): void;
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openHistoryNext(): void;
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openLinkPrev(): void;
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openLinkNext(): void;
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}
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const REL_PATTERN: {[key: string]: RegExp} = {
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prev: /^(?:prev(?:ious)?|older)\b|\u2039|\u2190|\xab|\u226a|<</i,
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next: /^(?:next|newer)\b|\u203a|\u2192|\xbb|\u226b|>>/i,
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};
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// Return the last element in the document matching the supplied selector
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// and the optional filter, or null if there are no matches.
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// eslint-disable-next-line func-style
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function selectLast<E extends Element>(
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selector: string,
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filter?: (e: E) => boolean,
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): E | null {
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let nodes = Array.from(
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window.document.querySelectorAll(selector) as NodeListOf<E>
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);
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if (filter) {
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nodes = nodes.filter(filter);
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}
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return nodes.length ? nodes[nodes.length - 1] : null;
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}
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export class NavigationPresenterImpl implements NavigationPresenter {
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openHistoryPrev(): void {
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window.history.back();
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}
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openHistoryNext(): void {
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window.history.forward();
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}
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openLinkPrev(): void {
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this.linkRel('prev');
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}
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openLinkNext(): void {
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this.linkRel('next');
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}
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// Code common to linkPrev and linkNext which navigates to the specified page.
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private linkRel(rel: 'prev' | 'next'): void {
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let link = selectLast<HTMLLinkElement>(`link[rel~=${rel}][href]`);
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if (link) {
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window.location.href = link.href;
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return;
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}
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const pattern = REL_PATTERN[rel];
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let a = selectLast<HTMLAnchorElement>(`a[rel~=${rel}][href]`) ||
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// `innerText` is much slower than `textContent`, but produces much better
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// (i.e. less unexpected) results
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selectLast('a[href]', lnk => pattern.test(lnk.innerText));
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if (a) {
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a.click();
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}
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}
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}
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