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"use client"; |
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|
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import { useEffect, useState } from "react"; |
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import { usePathname } from "next/navigation"; |
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|
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interface Heading { |
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id: string; |
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text: string; |
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level: number; |
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} |
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|
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export default function TableOfContents() { |
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const [headings, setHeadings] = useState<Heading[]>([]); |
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const [activeId, setActiveId] = useState<string>(""); |
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const pathname = usePathname(); |
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|
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useEffect(() => { |
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setHeadings([]); |
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setActiveId(""); |
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|
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const timer = setTimeout(() => { |
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const article = document.querySelector("article"); |
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if (!article) return; |
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|
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const elements = article.querySelectorAll("h2, h3"); |
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const items: Heading[] = []; |
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|
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elements.forEach((el) => { |
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if (!el.id) { |
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el.id = |
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el.textContent |
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?.toLowerCase() |
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.replace(/[^a-z0-9]+/g, "-") |
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.replace(/(^-|-$)/g, "") || ""; |
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} |
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|
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items.push({ |
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id: el.id, |
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text: el.textContent || "", |
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level: el.tagName === "H2" ? 2 : 3, |
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}); |
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}); |
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|
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setHeadings(items); |
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}, 100); |
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|
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return () => clearTimeout(timer); |
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}, [pathname]); |
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|
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useEffect(() => { |
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if (headings.length === 0) return; |
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|
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const observer = new IntersectionObserver( |
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(entries) => { |
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entries.forEach((entry) => { |
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if (entry.isIntersecting) { |
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setActiveId(entry.target.id); |
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} |
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}); |
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}, |
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{ rootMargin: "-80px 0px -80% 0px" } |
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); |
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|
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headings.forEach((heading) => { |
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const el = document.getElementById(heading.id); |
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if (el) observer.observe(el); |
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}); |
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|
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return () => observer.disconnect(); |
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}, [headings]); |
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|
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if (headings.length === 0) return null; |
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|
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return ( |
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<nav className="w-56 shrink-0 hidden xl:block"> |
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<div className="sticky top-8 p-4"> |
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<h4 className="text-sm font-semibold text-surface-900 dark:text-surface-100 mb-4"> |
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On This Page |
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</h4> |
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<ul className="space-y-2 text-sm"> |
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{headings.map((heading) => ( |
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<li key={heading.id}> |
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<a |
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href={`#${heading.id}`} |
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className={`block transition-colors ${ |
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heading.level === 3 ? "pl-3" : "" |
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} ${ |
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activeId === heading.id |
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? "text-surface-900 dark:text-surface-100 font-medium" |
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: "text-surface-500 dark:text-surface-400 hover:text-surface-900 dark:hover:text-surface-100" |
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}`} |
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> |
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{heading.text} |
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</a> |
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</li> |
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))} |
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</ul> |
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</div> |
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</nav> |
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); |
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} |