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-rw-r--r--examples/design-system/packages/acme-utils/src/usePrevious.tsx17
1 files changed, 17 insertions, 0 deletions
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 };