function Scrubber(values, { // https://observablehq.com/@mbostock/scrubber format = value => value, initial = 0, delay = null, autoplay = true, loop = true, alternate = false } = {}) { values = Array.from(values); const form = html``; let timer = null; let direction = 1; function start() { form.b.textContent = "Zastavit"; timer = delay === null ? requestAnimationFrame(tick) : setInterval(tick, delay); } function stop() { form.b.textContent = "Spustit"; if (delay === null) cancelAnimationFrame(timer); else clearInterval(timer); timer = null; } function tick() { if (delay === null) timer = requestAnimationFrame(tick); if (form.i.valueAsNumber === (direction > 0 ? values.length - 1 : direction < 0 ? 0 : NaN)) { if (!loop) return stop(); if (alternate) direction = -direction; } form.i.valueAsNumber = (form.i.valueAsNumber + direction + values.length) % values.length; form.i.dispatchEvent(new CustomEvent("input", {bubbles: true})); } form.i.oninput = event => { if (event && event.isTrusted && timer) form.b.onclick(); form.value = values[form.i.valueAsNumber]; form.o.value = format(form.value, form.i.valueAsNumber, values); }; form.b.onclick = () => { if (timer) return stop(); direction = alternate && form.i.valueAsNumber === values.length - 1 ? -1 : 1; form.i.valueAsNumber = (form.i.valueAsNumber + direction) % values.length; form.i.dispatchEvent(new CustomEvent("input", {bubbles: true})); start(); }; form.i.oninput(); if (autoplay) start(); else stop(); disposal(form).then(stop); return form; }

Purpose-built for displays of data