57 lines
4.3 KiB
JavaScript
57 lines
4.3 KiB
JavaScript
// App-shell niceties that do not belong to any one tab: offline notice and an accessibility layer
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// (names for icon-only buttons, a skip link, keyboard handling and focus for sheets).
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(function () {
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// ---- Offline notice
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const bar = document.createElement('div');
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bar.id = 'offline'; bar.setAttribute('role', 'status'); bar.hidden = true;
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bar.textContent = 'You are offline. Showing what was saved on this device; changes will not sync until you are back online.';
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document.body.appendChild(bar);
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const sync = () => { bar.hidden = navigator.onLine; };
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addEventListener('online', sync); addEventListener('offline', sync); sync();
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// ---- Skip link and landmarks
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const skip = document.createElement('a');
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skip.href = '#view'; skip.className = 'skip'; skip.textContent = 'Skip to content';
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skip.addEventListener('click', e => { e.preventDefault(); const v = document.getElementById('view'); if (v) { v.setAttribute('tabindex', '-1'); v.focus(); } });
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document.body.insertBefore(skip, document.body.firstChild);
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const nav = document.getElementById('nav'); if (nav && !nav.getAttribute('aria-label')) nav.setAttribute('aria-label', 'Main');
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// ---- Give every button or link that has only an icon a name (from its title, tooltip, id or class)
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const NAMES = { more: 'More', navcol: 'Collapse the menu', sx: 'Cancel', x: 'Close', close: 'Close', back: 'Back', fwd: 'Forward', menu: 'Menu', play: 'Play', pause: 'Pause', next: 'Next', prev: 'Previous', shuffle: 'Shuffle', repeat: 'Repeat', send: 'Send', clip: 'Attach a file', lyrics: 'Lyrics', full: 'Full screen', refresh: 'Refresh', ext: 'Open in a new tab' };
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const named = el => (el.getAttribute('aria-label') || el.getAttribute('aria-labelledby') || el.textContent.trim() || el.getAttribute('title') || '');
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function label(root) {
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root.querySelectorAll('button, a[href], [role="button"]').forEach(el => {
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if (named(el)) { if (!el.getAttribute('aria-label') && !el.textContent.trim()) el.setAttribute('aria-label', el.getAttribute('title')); return; }
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const key = (el.id || '').replace(/^(btn|b)-?/, '') || [...el.classList].find(c => NAMES[c]) || '';
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const l = NAMES[key] || NAMES[el.id] || (el.querySelector('img[alt]') || {}).alt;
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if (l) el.setAttribute('aria-label', l);
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});
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root.querySelectorAll('input:not([type=hidden]):not([type=checkbox]):not([type=radio]), select, textarea').forEach(el => {
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if (el.getAttribute('aria-label') || el.getAttribute('aria-labelledby') || (el.id && document.querySelector(`label[for="${CSS.escape(el.id)}"]`)) || el.closest('label')) return;
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const l = el.getAttribute('placeholder') || el.getAttribute('title'); if (l) el.setAttribute('aria-label', l);
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});
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}
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let pending = false;
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new MutationObserver(() => { if (pending) return; pending = true; requestAnimationFrame(() => { pending = false; label(document.body); }); })
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.observe(document.body, { childList: true, subtree: true });
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label(document.body);
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// ---- Sheets (bottom sheets and dialogs): Escape closes, focus moves in and returns, Tab stays inside
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let lastFocus = null;
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new MutationObserver(() => {
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const s = document.getElementById('sheet');
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if (s && !s._a11y) { s._a11y = true; lastFocus = document.activeElement; setTimeout(() => { if (!s.contains(document.activeElement)) { const f = s.querySelector('input:not([type=hidden]), textarea, select, button'); if (f) f.focus(); } }, 50); }
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if (!s && lastFocus) { try { lastFocus.focus(); } catch {} lastFocus = null; }
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}).observe(document.body, { childList: true });
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addEventListener('keydown', e => {
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const s = document.getElementById('sheet'); if (!s) return;
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if (e.key === 'Escape' && typeof closeSheet === 'function') { e.preventDefault(); closeSheet(); return; }
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if (e.key !== 'Tab') return;
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const f = [...s.querySelectorAll('a[href], button:not([disabled]), input:not([type=hidden]):not([disabled]), select, textarea, [tabindex]:not([tabindex="-1"])')].filter(x => x.offsetParent !== null);
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if (!f.length) return;
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const first = f[0], last = f[f.length - 1];
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if (e.shiftKey && document.activeElement === first) { e.preventDefault(); last.focus(); }
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else if (!e.shiftKey && (document.activeElement === last || !s.contains(document.activeElement))) { e.preventDefault(); first.focus(); }
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});
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})();
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