useeffect get previous value code example
Example: useeffect previous state
const Component = (props) => {
const {receiveAmount, sendAmount } = props
// declare usePrevious hook
const usePrevious = (value) => {
const ref = useRef();
useEffect(() => {
ref.current = value;
});
return ref.current;
}
// call usePrevious hook on component state variables to store previousState
const prevAmount = usePrevious({receiveAmount, sendAmount});
// useEffect hook to detect change of state variables
useEffect(() => {
if(prevAmount.receiveAmount !== receiveAmount) {
// process here
}
if(prevAmount.sendAmount !== sendAmount) {
// process here
}
}, [receiveAmount, sendAmount])
}