Refresh thread replies periodically & when refocusing window (#36547)

app/javascript/mastodon/hooks/useInterval.ts

@@ -0,0 +1,39 @@
+import { useEffect, useLayoutEffect, useRef } from 'react';
+
+/**
+ * Hook to create an interval that invokes a callback function
+ * at a specified delay using the setInterval API.
+ * Based on https://usehooks-ts.com/react-hook/use-interval
+ */
+export function useInterval(
+  callback: () => void,
+  {
+    delay,
+    isEnabled = true,
+  }: {
+    delay: number;
+    isEnabled?: boolean;
+  },
+) {
+  // Write callback to a ref so we can omit it from
+  // the interval effect's dependency array
+  const callbackRef = useRef(callback);
+  useLayoutEffect(() => {
+    callbackRef.current = callback;
+  }, [callback]);
+
+  // Set up the interval.
+  useEffect(() => {
+    if (!isEnabled) {
+      return;
+    }
+
+    const intervalId = setInterval(() => {
+      callbackRef.current();
+    }, delay);
+
+    return () => {
+      clearInterval(intervalId);
+    };
+  }, [delay, isEnabled]);
+}