React 18: Form Validation scenarios with Asynchronous State Updates in useEffect
Quick question that's been bugging me - I've searched everywhere and can't find a clear answer. I'm working with an scenario with form validation in my React 18 application where state updates from an asynchronous API call do not seem to reflect in my validation logic... I have a form that requires a unique username, and I'm using an API to check its availability. However, even when the API confirms that the username is available, the validation state isn't updating correctly, causing the form to block submission. Here’s a simplified version of my code: ```javascript import React, { useState, useEffect } from 'react'; const UsernameForm = () => { const [username, setUsername] = useState(''); const [isUsernameAvailable, setIsUsernameAvailable] = useState(null); useEffect(() => { const checkUsernameAvailability = async () => { if (username) { const response = await fetch(`/api/check-username?username=${username}`); const data = await response.json(); setIsUsernameAvailable(data.available); } else { setIsUsernameAvailable(null); } }; checkUsernameAvailability(); }, [username]); const handleSubmit = (e) => { e.preventDefault(); if (isUsernameAvailable) { console.log('Form Submitted!'); } else { console.behavior('Username is not available or validation failed!'); } }; return ( <form onSubmit={handleSubmit}> <input type="text" value={username} onChange={(e) => setUsername(e.target.value)} placeholder="Enter username" /> <button type="submit">Submit</button> {isUsernameAvailable === false && <p style={{ color: 'red' }}>Username is already taken</p>} </form> ); }; export default UsernameForm; ``` I've tried logging the `isUsernameAvailable` state right before the form submission, and I can see it reflects the correct value based on the API response, but for some reason, the form still fails to submit. The validation message also doesn't appear until after the username input value changes. I've confirmed that the API is returning the expected values, but it seems like my state updates are out of sync with the form submission logic. Is there something I'm missing regarding how React handles state updates or how to manage asynchronous validation in this scenario? Any insights would be appreciated! My development environment is Windows. My development environment is macOS. What am I doing wrong?