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author简律纯 <hsiangnianian@outlook.com>2023-04-28 01:47:57 +0800
committer简律纯 <hsiangnianian@outlook.com>2023-04-28 01:47:57 +0800
commit8b2c4a38a461ff5ecc95972291bc711e2c5dec9a (patch)
tree29f552e3df949073e21bf5c76d7abc3044830ec6 /examples/with-changesets/packages/acme-utils/src/usePrevious.tsx
parentfc8c5fdce62fb229202659408798a7b6c98f6e8b (diff)
downloadHydroRoll-8b2c4a38a461ff5ecc95972291bc711e2c5dec9a.tar.gz
HydroRoll-8b2c4a38a461ff5ecc95972291bc711e2c5dec9a.zip
Diffstat (limited to 'examples/with-changesets/packages/acme-utils/src/usePrevious.tsx')
-rw-r--r--examples/with-changesets/packages/acme-utils/src/usePrevious.tsx17
1 files changed, 17 insertions, 0 deletions
diff --git a/examples/with-changesets/packages/acme-utils/src/usePrevious.tsx b/examples/with-changesets/packages/acme-utils/src/usePrevious.tsx
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+++ b/examples/with-changesets/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 };