React: Handling Dynamic Form Fields with Controlled Components - Unexpected State Resets
I've been researching this but I recently switched to I'm sure I'm missing something obvious here, but I'm working on a React application (version 17.0.2) where I need to create a dynamic form that allows users to add or remove fields at runtime. I'm using controlled components to manage the state of each form field, but I'm facing an issue where the state resets unexpectedly when I add a new field. Here's what I've tried: I've set up a state variable called `formFields` to keep track of an array of field values. When the user clicks 'Add Field', I push a new value to this array and then update the state. However, every time I add a new field, the previously filled fields lose their values, which is not the expected behavior. Here's a simplified version of my code: ```javascript import React, { useState } from 'react'; const DynamicForm = () => { const [formFields, setFormFields] = useState(['']); const handleFieldChange = (index, event) => { const values = [...formFields]; values[index] = event.target.value; setFormFields(values); }; const addField = () => { setFormFields([...formFields, '']); }; return ( <div> {formFields.map((field, index) => ( <input key={index} type="text" value={field} onChange={(event) => handleFieldChange(index, event)} /> ))} <button onClick={addField}>Add Field</button> </div> ); }; export default DynamicForm; ``` When I add a new field, I see that the first field resets to an empty string instead of retaining its value, which is confusing. My current understanding is that I should be managing the state correctly; however, I'm not sure why I'm losing the values. Also, there's a warning in the console stating: "Warning: Each child in a list should have a unique 'key' prop." I suspect this might be related to my issue with state management. Has anyone experienced similar issues with controlled components in React? Any insights on how to correctly manage dynamic form fields without losing state would be greatly appreciated! I'm working on a application that needs to handle this. What am I doing wrong? Thanks for any help you can provide! I'm coming from a different tech stack and learning Javascript. Any advice would be much appreciated. Am I missing something obvious?