React 18: implementing Conditional Rendering and Key Prop Issues in a Dynamic List
I've been struggling with this for a few days now and could really use some help. I'm maintaining legacy code that I'm integrating two systems and I'm trying to implement I'm migrating some code and I tried several approaches but none seem to work..... I've searched everywhere and can't find a clear answer... I'm working with issues with conditional rendering in my React 18 application where I'm dynamically adding and removing items from a list. The question arises when I try to render a component based on a condition, such as showing a detailed view for a selected item in the list. When I remove an item from the list, the detailed view sometimes shows the wrong item's details, and I suspect it has to do with how I'm using the `key` prop. Here's a simplified version of my code: ```javascript import React, { useState } from 'react'; const ItemList = () => { const [items, setItems] = useState(['Item 1', 'Item 2', 'Item 3']); const [selectedItem, setSelectedItem] = useState(null); const handleSelect = (item) => { setSelectedItem(item); }; const handleRemove = (item) => { setItems(items.filter(i => i !== item)); if (selectedItem === item) { setSelectedItem(null); } }; return ( <div> <ul> {items.map(item => ( <li key={item}> <span onClick={() => handleSelect(item)}>{item}</span> <button onClick={() => handleRemove(item)}>Remove</button> </li> ))} </ul> {selectedItem && <div>Details for {selectedItem}</div>} </div> ); }; export default ItemList; ``` After removing an item, I noticed that the details displayed might still reference the removed item instead of updating correctly to the current selection. I checked my `key` props and ensured they are unique, but I still encounter inconsistencies. I also tried using `React.memo` for the detailed view component to optimize performance, but that didn’t resolve the scenario. Is there something I’m overlooking with the state updates or how React reconciles the DOM? How can I ensure that the selected item always corresponds to the current list state? Any insights would be greatly appreciated! This is part of a larger service I'm building. What am I doing wrong? My development environment is Ubuntu 20.04. I'm open to any suggestions. I'm on CentOS using the latest version of Javascript. Has anyone else encountered this? How would you solve this? This issue appeared after updating to Javascript stable. Any pointers in the right direction? I'm working in a Debian environment. Has anyone else encountered this? For reference, this is a production REST API.