From 8b2c4a38a461ff5ecc95972291bc711e2c5dec9a Mon Sep 17 00:00:00 2001
From: 简律纯 <hsiangnianian@outlook.com>
Date: Fri, 28 Apr 2023 01:47:57 +0800
Subject:

---
 .../packages/acme-utils/src/usePrevious.tsx             | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 examples/design-system/packages/acme-utils/src/usePrevious.tsx

(limited to 'examples/design-system/packages/acme-utils/src/usePrevious.tsx')

diff --git a/examples/design-system/packages/acme-utils/src/usePrevious.tsx b/examples/design-system/packages/acme-utils/src/usePrevious.tsx
new file mode 100644
index 0000000..8024464
--- /dev/null
+++ b/examples/design-system/packages/acme-utils/src/usePrevious.tsx
@@ -0,0 +1,17 @@
+import * as React from "react";
+
+function usePrevious<T>(value: T) {
+  // The ref object is a generic container whose current property is mutable ...
+  // ... and can hold any value, similar to an instance property on a class
+  const ref = React.useRef<T>(value);
+
+  // Store current value in ref
+  React.useEffect(() => {
+    ref.current = value;
+  }, [value]); // Only re-run if value changes
+
+  // Return previous value (happens before update in useEffect above)
+  return ref.current;
+}
+
+export { usePrevious };
-- 
cgit v1.2.3-70-g09d2

