This is a popular question among all the new react developers but somehow I'm not able to understand the logic behind available solutions. I'm trying to update the state variable using hooks and trying it read the updated value but always it returns a previous value instead of new value. Below is the sequence of my code execution.
onClick={setTransactionAccountId}
on button click, it executes the below code and updates the state but the console.log
shows the old value.
const [accountId, setAccountId] = useState(0);
const setTransactionAccountId = e => {
console.log("Clicked ID:", e.currentTarget.value);
setAccountId(e.currentTarget.value);
console.log("accountId:", accountId);
};
console log:
Clicked ID: 0 accountId: 0
Clicked ID: 1 accountId: 0
could anyone please tell me the reason behind this behaviour and how to tackle it.
TL;DR: useState is an asynchronous hook and it doesn't change the state immediately, it has to wait for the component to re-render. useRef is a synchronous hook that updates the state immediately and persists its value through the component's lifecycle, but it doesn't trigger a re-render.
If you want to update data and cause a UI update, useState is your Hook. If you need some kind of data container throughout the component's lifecycle without causing render cycles on mutating your variable, then useRef is your solution.
accountId
won't have been updated this render. You have to wait for the next render for it to be updated. accountId
only gets populated at the top of the function component when useState
is called. You're in the middle of the render. If you need the actual value, keep pulling it out of e.currentTarget.value
.
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