From 47587812b809fee2a95c76266d9d0e42fc4ac1ca Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Tue, 15 Jun 2021 14:14:28 +0800
Subject: ...

---
 FrontEnd/src/utilities/useScrollToTop.ts | 43 ++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 FrontEnd/src/utilities/useScrollToTop.ts

(limited to 'FrontEnd/src/utilities/useScrollToTop.ts')

diff --git a/FrontEnd/src/utilities/useScrollToTop.ts b/FrontEnd/src/utilities/useScrollToTop.ts
new file mode 100644
index 00000000..892e3545
--- /dev/null
+++ b/FrontEnd/src/utilities/useScrollToTop.ts
@@ -0,0 +1,43 @@
+import React from "react";
+import { fromEvent } from "rxjs";
+import { filter, throttleTime } from "rxjs/operators";
+
+function useScrollToTop(
+  handler: () => void,
+  enable = true,
+  option = {
+    maxOffset: 50,
+    throttle: 1000,
+  }
+): void {
+  const handlerRef = React.useRef<(() => void) | null>(null);
+
+  React.useEffect(() => {
+    handlerRef.current = handler;
+
+    return () => {
+      handlerRef.current = null;
+    };
+  }, [handler]);
+
+  React.useEffect(() => {
+    const subscription = fromEvent(window, "scroll")
+      .pipe(
+        filter(() => {
+          return window.scrollY <= option.maxOffset;
+        }),
+        throttleTime(option.throttle)
+      )
+      .subscribe(() => {
+        if (enable) {
+          handlerRef.current?.();
+        }
+      });
+
+    return () => {
+      subscription.unsubscribe();
+    };
+  }, [enable, option.maxOffset, option.throttle]);
+}
+
+export default useScrollToTop;
-- 
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