Show timer in bubble if timed activity exists

src/js/components/shared/hooks.js

@@ -0,0 +1,18 @@
+import { useEffect, useRef } from "react"
+
+export function useInterval(callback, delay) {
+  const savedCallback = useRef()
+
+  useEffect(() => {
+    savedCallback.current = callback
+  })
+
+  useEffect(() => {
+    function tick() {
+      savedCallback.current()
+    }
+
+    let id = setInterval(tick, delay)
+    return () => clearInterval(id)
+  }, [delay])
+}