31:[] 2f:{"title":"Transit of Mercury (2019)","cells":[{"id":0,"value":"md`# Transit of Mercury (2019)\n\n*See also: [Full disk](https://observablehq.com/@jashkenas/transit-of-mercury-full-disk-2019)*\n\n*Source: [NASA](https://mercurytransit.gsfc.nasa.gov/)*`","pinned":false,"hidden":false,"mode":"ojs"},{"id":13,"value":"viewof frame = {\n const form = html``;\n const speed = 83;\n function tick() {\n form.i.value = (form.i.valueAsNumber + 1) % frames.length;\n form.i.dispatchEvent(new CustomEvent(\"input\", { bubbles: true }));\n }\n let interval = setInterval(tick, speed);\n form.b.onclick = () => {\n if (interval) {\n form.b.textContent = \"Play\";\n interval = clearInterval(interval);\n } else {\n form.b.textContent = \"Pause\";\n interval = setInterval(tick, speed);\n }\n };\n form.i.oninput = event => {\n if (!(event instanceof CustomEvent) && interval) form.b.click();\n form.value = form.o.value = form.i.valueAsNumber;\n };\n form.value = form.o.value = 0;\n invalidation.then(() => clearInterval(interval));\n return form;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":23,"value":"transit = html`

\n ${frames[frame]}\n

`","pinned":false,"hidden":false,"mode":"ojs"},{"id":16,"value":"frames = Array.from({ length: 515 }, (_, i) =>\n Object.assign(new Image(), {\n src: `https://mercurytransit.gsfc.nasa.gov/data/2019/data/Mercury19_AIA96s_171/Track/${(\n i + 1\n )\n .toString()\n .padStart(4, '0')}.jpg`\n })\n)","pinned":false,"hidden":false,"mode":"ojs"},{"id":94,"value":"html``","pinned":false,"hidden":false,"mode":"ojs"}],"files":"$W31","stdlib":"1","titling":"auto"}