Added settings, proper record renaming

static/js/mbus.mjs

@@ -0,0 +1,29 @@
+export class MessageBus {
+	constructor() {
+		this.bus = new EventTarget()
+		this.counter = 0
+		this.fnmap = new Map()
+	}
+
+	subscribe(eventName, fn) {
+		this.counter++
+		this.bus.addEventListener(eventName, fn)
+		this.fnmap.set(this.counter, { eventName, fn })
+		return this.counter
+	}
+
+	unsubscribe(mappedID) {
+		const mapped = this.fnmap.get(mappedID)
+		if (mapped === undefined) {
+			console.warn('unsubscribe, no such mapped ID', mappedID)
+			return
+		}
+		this.fnmap.delete(mappedID)
+		this.bus.removeEventListener(mapped.eventName, mapped.fn)
+	}
+
+	dispatch(eventName, data) {
+		console.debug('mbus', eventName, data)
+		this.bus.dispatchEvent(new CustomEvent(eventName, { detail: data }))
+	}
+}