I am making a React application for a currency converter website. I have two <input>
fields where the user can input the number to get the exchange rate as shown here:
Screenshot of Component
The <input>
fields are as follows:
<>
<input
id="1"
placeholder="0"
type="number"
value={state1.value}
onChange={handleChange}
disabled={loading}
/>
// rest of the component
<input
id="2"
placeholder="0"
type="number"
value={state2.value}
onChange={handleChange}
disabled={loading}
/>
The states for the input fields are:
const [state1, setState1] = useState({
value: '',
currency: 'USD',
src: 'https://hatscripts.github.io/circle-flags/flags/us.svg',
});
const [state2, setState2] = useState({
value: '',
currency: 'INR',
src: 'https://hatscripts.github.io/circle-flags/flags/in.svg',
});
I want the state2
to be updated when the user types in state1
. And vice-versa. I don't want the auto-update of state2
again changing state1
. The state change should happen only when the user gives input.
I have tried using session state to avoid unnecessary API calls. It solves the problem except for the infinite recursion.
I have already written a useEffect
for state1
which works as expected. Now I want to do the same for state2
without an infinite useEffect loop.
async function fetchCurrencyRate1(from, to) {
setLoading(true);
try {
const response = await axios.get('http://localhost:4000/convert', {
params: {
from: from.currency,
to: to.currency,
},
});
setState2((state2) => ({
...state2,
value: (from.value * response.data.value).toFixed(4),
}));
console.log(response.data);
} catch (error) {
console.error(error);
}
setLoading(false);
}
useEffect(() => {
setTimeout(() => {
state1.value && fetchCurrencyRate1(state1, { ...state2 });
if (state1.value === '') setState2({ ...state2, value: '' });
}, 2000);
}, [state1]);
The infinite render occurs because the useEffect
of state1
will fire each time state1
take a new value and since inside the effect you update state2
and this triggers useEffect
of state2
and the code there updates state1
then useEffect
of state1
will be called infinitely because state1
is an object so its value is always new.
you don't need useEffect
for that, also you don't want to rerender the component twice on each input change you can simply make two separate handleChange
functions for each input and make your logic in each one of them
something like this:
const handleChangeOne = async (e) => {
// you can fetch data here instead
setState1((prev) => {
return {
...prev,
value: e.target.value,
};
});
setState2((prev) => {
return {
...prev,
value: (from.value * response.data.value).toFixed(4),
};
});
};
const handleChangeTwo = async (e) => {
// fetch data
setState2((prev) => {
return {
...prev,
value: Number(e.target.value),
};
});
setState1((prev) => {
//
return {
...prev,
value: (from.value * response.data.value).toFixed(4),
};
});
};