Notification when cell is re-run by the user?

Tooling Pluto
,
2

@ssfrr

Here is a minimal working example I managed to make work using the MutationObserver API

@htl """
<script id="osctest">
let div = this ?? document.createElement("div")
if (this == null) {
	div.classList.toggle('oscillator-container',true)
	let id = $(join(rand("abcdefghilmnopqrstuvz",8)))
	div.id = id

	div.ctx = new AudioContext()
	div.osc = new OscillatorNode(div.ctx)
	div.osc.connect(div.ctx.destination); div.osc.start()

	
	const observer = new MutationObserver((entries) => {
		for (const entry of entries) {
			for (const added of entry.addedNodes) {
				if (added instanceof Element && added.classList.contains('oscillator-container') && added.id != id) {
					console.log('Found a manual rerun! Disconnecting...')
					div.osc.stop()
					div.ctx.close()
					observer.disconnect()
				}
			}
		}
	})
	observer.observe(currentScript.closest('div.raw-html-wrapper'), {childList: true})
}
div.osc.frequency.setValueAtTime($freq, div.ctx.currentTime)

return div
</script>
"""

The main idea is to assign a unique id to the div you are generating in the script only upon manual re-run (when this == null) and then attach a MutationObserver to the pluto-output wrapper that monitors addition and deletion of children.
As soon as a new div with the oscillator-container class is added and has an id which is different from the one you generated together with the MutationObserver, I assume that a manual rerun has been triggered and I can disconnect everything.

Seems to work, don’t know if there are better ways to achieve this though.