feat(shared/hooks): useOldValue

Author: mengxinssfd

packages/shared/src/hooks/index.ts

@@ -20,3 +20,4 @@ export * from './useUniqueRoot';
 export * from './useStateRef';
 export * from './useFollowingState';
 export * from './useOnlineStatus';
+export * from './useOldValue';

packages/shared/src/hooks/useOldValue.ts

@@ -0,0 +1,10 @@
+import { useValueWithPrev } from './useValueWithPrev';
+
+/**
+ * 类似于 useDeferredValue
+ * useDeferredValue 起初会跟原值一样，当原值改变以后会落后于原值，最后会额外更新一次自身值
+ * 跟 useDeferredValue 不一样的是起初值是 undefined，最后不会额外更新自身值
+ */
+export function useOldValue<T>(value: T): undefined | T {
+  return useValueWithPrev(value)[1];
+}