Why is key Needed in React?

key is a special prop in React used to uniquely identify elements in lists. It helps React properly manage element state when they're added, removed or reordered. This is especially important when working with dynamically changing data.

Why key?

• Render optimization. When list elements change, React uses key to determine which elements changed, were added or removed. This allows React to minimize DOM changes and improve performance.

• Unique identification. Each list element must have a unique key so React can properly track and manage each element. This is important for correct display and efficient updates.

key Usage Example

const items = ["apple", "banana", "cherry"];

function FruitList() {
  return (
    <ul>
      {items.map((item, index) => (
        <li key={index}>{item}</li>
      ))}
    </ul>
  );
}