diff options
Diffstat (limited to 'examples/design-system/packages/acme-utils/src/usePrevious.tsx')
| -rw-r--r-- | examples/design-system/packages/acme-utils/src/usePrevious.tsx | 17 |
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 }; |
