46 lines
1.5 KiB
TypeScript
46 lines
1.5 KiB
TypeScript
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const bufferPx = 150
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const observer = new IntersectionObserver((entries) => {
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for (const entry of entries) {
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const slug = entry.target.id
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const tocEntryElement = document.querySelector(`a[data-for="${slug}"]`)
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const windowHeight = entry.rootBounds?.height
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if (windowHeight && tocEntryElement) {
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if (entry.boundingClientRect.y < windowHeight) {
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tocEntryElement.classList.add("in-view")
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} else {
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tocEntryElement.classList.remove("in-view")
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}
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}
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}
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})
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function toggleToc(this: HTMLElement) {
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this.classList.toggle("collapsed")
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const content = this.nextElementSibling as HTMLElement | undefined
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if (!content) return
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content.classList.toggle("collapsed")
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content.style.maxHeight = content.style.maxHeight === "0px" ? content.scrollHeight + "px" : "0px"
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}
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function setupToc() {
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const toc = document.getElementById("toc")
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if (toc) {
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const collapsed = toc.classList.contains("collapsed")
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const content = toc.nextElementSibling as HTMLElement | undefined
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if (!content) return
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content.style.maxHeight = collapsed ? "0px" : content.scrollHeight + "px"
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toc.addEventListener("click", toggleToc)
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window.addCleanup(() => toc.removeEventListener("click", toggleToc))
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}
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}
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window.addEventListener("resize", setupToc)
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document.addEventListener("nav", () => {
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setupToc()
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// update toc entry highlighting
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observer.disconnect()
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const headers = document.querySelectorAll("h1[id], h2[id], h3[id], h4[id], h5[id], h6[id]")
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headers.forEach((header) => observer.observe(header))
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})
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