fen
3460d54fce
The initial refresh() ran before the mobile layout settled (media queries, fonts, async highlighting) and under-measured the content, leaving #jumpnav hidden on long pastes at 375x812 until a resize event. Re-check after a double rAF, on window load, after 300ms, and via a ResizeObserver on document.body for late content growth. Editor textarea scroller unchanged.
52 lines
1.9 KiB
JavaScript
52 lines
1.9 KiB
JavaScript
/* #267: jump to top / bottom controls for long content.
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Paste view scrolls the window; the /new editor scrolls its textarea.
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The active scroller is chosen via data-jump-scroll on the script tag. */
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(function () {
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var nav = document.getElementById('jumpnav');
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if (!nav) return;
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var scroller = window;
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var sel = nav.dataset.jumpScroll;
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if (sel) scroller = document.querySelector(sel);
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function el() {
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return scroller === window ? document.scrollingElement : scroller;
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}
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function isLarge() {
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var e = el();
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if (!e) return false;
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var visible = scroller === window ? window.innerHeight : e.clientHeight;
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return e.scrollHeight > visible * 2;
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}
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function refresh() {
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nav.classList.toggle('hidden', !isLarge());
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}
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function jump(toTop) {
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var e = el();
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if (!e) return;
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if (scroller === window) {
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window.scrollTo({ top: toTop ? 0 : e.scrollHeight });
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} else {
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e.scrollTop = toTop ? 0 : e.scrollHeight;
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}
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}
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nav.addEventListener('click', function (ev) {
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var b = ev.target.closest('[data-jump]');
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if (!b) return;
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ev.preventDefault();
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jump(b.dataset.jump === 'top');
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});
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window.addEventListener('resize', refresh);
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if (scroller !== window && scroller) scroller.addEventListener('input', refresh);
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refresh();
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/* #282: the first evaluation can run before the layout settles (media
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queries, web fonts, async highlighting) and under-measure the content,
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leaving the nav hidden on long pages. Re-check once a real layout exists
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and after load; the ResizeObserver also catches late content growth. */
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requestAnimationFrame(function () { requestAnimationFrame(refresh); });
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window.addEventListener('load', refresh);
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window.setTimeout(refresh, 300);
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if (window.ResizeObserver && scroller === window && document.body) {
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new ResizeObserver(refresh).observe(document.body);
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}
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})();
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