revalidate config changes, check on focus changes

src/utils/hooks/window-focus.js

@@ -0,0 +1,26 @@
+import { useState, useEffect } from "react";
+
+const hasFocus = () => typeof document !== "undefined" && document.hasFocus();
+
+const useWindowFocus = () => {
+  const [focused, setFocused] = useState(hasFocus);
+
+  useEffect(() => {
+    setFocused(hasFocus());
+
+    const onFocus = () => setFocused(true);
+    const onBlur = () => setFocused(false);
+
+    window.addEventListener("focus", onFocus);
+    window.addEventListener("blur", onBlur);
+
+    return () => {
+      window.removeEventListener("focus", onFocus);
+      window.removeEventListener("blur", onBlur);
+    };
+  }, []);
+
+  return focused;
+};
+
+export default useWindowFocus;