I'm trying to use the throttle
method from lodash
in a functional component, e.g.:
const App = () => {
const [value, setValue] = useState(0)
useEffect(throttle(() => console.log(value), 1000), [value])
return (
<button onClick={() => setValue(value + 1)}>{value}</button>
)
}
Since the method inside useEffect
is redeclared at each render, the throttling effect does not work.
Does anyone have a simple solution (without moving the throttle implementation outside of the component) ?
After some time passed I'm sure it's much easier to handle things by your own with setTimeout/clearTimeout
(and moving that into separate custom hook) than working with functional helpers. Handling later one creates additional challenges right after we apply that to useCallback
that can be recreated because of dependency change but we don't want to reset delay running.
original answer below
you may(and probably need) useRef
to store value between renders. Just like it's suggested for timers
Something like that
const App = () => {
const [value, setValue] = useState(0)
const throttled = useRef(throttle((newValue) => console.log(newValue), 1000))
useEffect(() => throttled.current(value), [value])
return (
<button onClick={() => setValue(value + 1)}>{value}</button>
)
}
As for useCallback
:
It may work too as
const throttled = useCallback(throttle(newValue => console.log(newValue), 1000), []);
But if we try to recreate callback once value
is changed:
const throttled = useCallback(throttle(() => console.log(value), 1000), [value]);
we may find it does not delay execution: once value
is changed callback is immediately re-created and executed.
So I see useCallback
in case of delayed run does not provide significant advantage. It's up to you.
[UPD] initially it was
const throttled = useRef(throttle(() => console.log(value), 1000))
useEffect(throttled.current, [value])
but that way throttled.current
has bound to initial value
(of 0) by closure. So it was never changed even on next renders.
So be careful while pushing functions into useRef
because of closure feature.