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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,93 +1,98 @@ | ||
| import type { MarkdownHeading } from 'astro'; | ||
| import type { FunctionalComponent } from 'preact'; | ||
| import { unescape } from 'html-escaper'; | ||
| import { useState, useEffect, useRef } from 'preact/hooks'; | ||
| import type { MarkdownHeading } from "astro"; | ||
| import type { FunctionalComponent } from "preact"; | ||
| import { unescape } from "html-escaper"; | ||
| import { useState, useEffect, useRef } from "preact/hooks"; | ||
|
|
||
| type ItemOffsets = { | ||
| id: string; | ||
| topOffset: number; | ||
| id: string; | ||
| topOffset: number; | ||
| }; | ||
|
|
||
| const TableOfContents: FunctionalComponent<{ headings: MarkdownHeading[] }> = ({ | ||
| headings = [], | ||
| headings = [], | ||
| }) => { | ||
| const toc = useRef<HTMLUListElement>(); | ||
| const onThisPageID = 'on-this-page-heading'; | ||
| const itemOffsets = useRef<ItemOffsets[]>([]); | ||
| const [currentID, setCurrentID] = useState('overview'); | ||
| useEffect(() => { | ||
| const getItemOffsets = () => { | ||
| const titles = document.querySelectorAll('article :is(h1, h2, h3, h4)'); | ||
| itemOffsets.current = Array.from(titles).map((title) => ({ | ||
| id: title.id, | ||
| topOffset: title.getBoundingClientRect().top + window.scrollY, | ||
| })); | ||
| }; | ||
| const toc = useRef<HTMLUListElement>(null); | ||
| const onThisPageID = "on-this-page-heading"; | ||
| const itemOffsets = useRef<ItemOffsets[]>([]); | ||
| const [currentID, setCurrentID] = useState("overview"); | ||
| useEffect(() => { | ||
| const getItemOffsets = () => { | ||
| const titles = document.querySelectorAll("article :is(h1, h2, h3, h4)"); | ||
| itemOffsets.current = Array.from(titles).map((title) => ({ | ||
| id: title.id, | ||
| topOffset: title.getBoundingClientRect().top + window.scrollY, | ||
| })); | ||
| }; | ||
|
|
||
| getItemOffsets(); | ||
| window.addEventListener('resize', getItemOffsets); | ||
| getItemOffsets(); | ||
| window.addEventListener("resize", getItemOffsets); | ||
|
|
||
| return () => { | ||
| window.removeEventListener('resize', getItemOffsets); | ||
| }; | ||
| }, []); | ||
| return () => { | ||
| window.removeEventListener("resize", getItemOffsets); | ||
| }; | ||
| }, []); | ||
|
|
||
| useEffect(() => { | ||
| if (!toc.current) return; | ||
| useEffect(() => { | ||
| if (!toc.current) return; | ||
|
|
||
| const setCurrent: IntersectionObserverCallback = (entries) => { | ||
| for (const entry of entries) { | ||
| if (entry.isIntersecting) { | ||
| const { id } = entry.target; | ||
| if (id === onThisPageID) continue; | ||
| setCurrentID(entry.target.id); | ||
| break; | ||
| } | ||
| } | ||
| }; | ||
| const setCurrent: IntersectionObserverCallback = (entries) => { | ||
| for (const entry of entries) { | ||
| if (entry.isIntersecting) { | ||
| const { id } = entry.target; | ||
| if (id === onThisPageID) continue; | ||
| setCurrentID(entry.target.id); | ||
| break; | ||
| } | ||
| } | ||
| }; | ||
|
|
||
| const observerOptions: IntersectionObserverInit = { | ||
| // Negative top margin accounts for `scroll-margin`. | ||
| // Negative bottom margin means heading needs to be towards top of viewport to trigger intersection. | ||
| rootMargin: '-100px 0% -66%', | ||
| threshold: 1, | ||
| }; | ||
| const observerOptions: IntersectionObserverInit = { | ||
| // Negative top margin accounts for `scroll-margin`. | ||
| // Negative bottom margin means heading needs to be towards top of viewport to trigger intersection. | ||
| rootMargin: "-100px 0% -66%", | ||
| threshold: 1, | ||
| }; | ||
|
|
||
| const headingsObserver = new IntersectionObserver(setCurrent, observerOptions); | ||
| const headingsObserver = new IntersectionObserver( | ||
| setCurrent, | ||
| observerOptions | ||
| ); | ||
|
|
||
| // Observe all the headings in the main page content. | ||
| document.querySelectorAll('article :is(h1,h2,h3)').forEach((h) => headingsObserver.observe(h)); | ||
| // Observe all the headings in the main page content. | ||
| document | ||
| .querySelectorAll("article :is(h1,h2,h3)") | ||
| .forEach((h) => headingsObserver.observe(h)); | ||
|
|
||
| // Stop observing when the component is unmounted. | ||
| return () => headingsObserver.disconnect(); | ||
| }, [toc.current]); | ||
| // Stop observing when the component is unmounted. | ||
| return () => headingsObserver.disconnect(); | ||
| }, [toc.current]); | ||
|
|
||
| const onLinkClick = (e) => { | ||
| setCurrentID(e.target.getAttribute('href').replace('#', '')); | ||
| }; | ||
| const onLinkClick = (e) => { | ||
| setCurrentID(e.target.getAttribute("href").replace("#", "")); | ||
| }; | ||
|
|
||
| return ( | ||
| <> | ||
| <h2 id={onThisPageID} className="heading"> | ||
| On this page | ||
| </h2> | ||
| <ul ref={toc}> | ||
| {headings | ||
| .filter(({ depth }) => depth > 1 && depth < 4) | ||
| .map((heading) => ( | ||
| <li | ||
| className={`header-link depth-${heading.depth} ${ | ||
| currentID === heading.slug ? 'current-header-link' : '' | ||
| }`.trim()} | ||
| > | ||
| <a href={`#${heading.slug}`} onClick={onLinkClick}> | ||
| {unescape(heading.text)} | ||
| </a> | ||
| </li> | ||
| ))} | ||
| </ul> | ||
| </> | ||
| ); | ||
| return ( | ||
| <> | ||
| <h2 id={onThisPageID} className="heading"> | ||
| On this page | ||
| </h2> | ||
| <ul ref={toc}> | ||
| {headings | ||
| .filter(({ depth }) => depth > 1 && depth < 4) | ||
| .map((heading) => ( | ||
| <li | ||
| className={`header-link depth-${heading.depth} ${ | ||
| currentID === heading.slug ? "current-header-link" : "" | ||
| }`.trim()} | ||
| > | ||
| <a href={`#${heading.slug}`} onClick={onLinkClick}> | ||
| {unescape(heading.text)} | ||
| </a> | ||
| </li> | ||
| ))} | ||
| </ul> | ||
| </> | ||
| ); | ||
| }; | ||
|
|
||
| export default TableOfContents; |