👀 Views: 30 💬 Answers: 1 📅 Created: 2025-07-05

reactjs form-validation controlled-components javascript

I've searched everywhere and can't find a clear answer. I'm trying to configure I'm working through a tutorial and I'm trying to implement I'm facing issues with form validation in a controlled component setup in React 18... I'm dynamically adding fields to a form, but the validation seems to be misbehaving when I update the state. Specifically, when I add a new field, it doesn't trigger a re-render correctly, and the validation messages aren't displaying as expected. Here's a simplified version of my code: ```jsx import React, { useState } from 'react'; const DynamicForm = () => { const [fields, setFields] = useState([{ value: '', error: '' }]); const handleChange = (index, event) => { const value = event.target.value; const newFields = [...fields]; newFields[index].value = value; newFields[index].error = validateField(value); setFields(newFields); }; const validateField = (value) => { return value.length < 3 ? 'Field must be at least 3 characters.' : ''; }; const addField = () => { setFields([...fields, { value: '', error: '' }]); }; return ( <div> {fields.map((field, index) => ( <div key={index}> <input type="text" value={field.value} onChange={(e) => handleChange(index, e)} /> {field.error && <span style={{ color: 'red' }}>{field.error}</span>} </div> ))} <button onClick={addField}>Add Field</button> </div> ); }; export default DynamicForm; ``` The issue occurs when I try to dynamically add a new field using the `addField` function. The new field appears, but when I type in it, the validation message does not show up immediately, and sometimes it also leads to a stale state where the previous fields' errors don't update correctly. I’ve tried using `useEffect` to watch for changes in the `fields` state, but it didn’t fix the issue. I also checked to ensure that my React version is 18.0.0 and all dependencies are compatible. Any insights on why this might be happening or how to properly manage dynamic field validation in a controlled component setup? I'm coming from a different tech stack and learning Javascript. Thanks in advance! I'm on CentOS using the latest version of Javascript. Cheers for any assistance! I'm on Debian using the latest version of Javascript. This issue appeared after updating to Javascript 3.10. Thanks for any help you can provide! This is happening in both development and production on Windows 11.