What is the purpose of the React key prop when reconciling lists, and why is using array index as a key considered problematic?

Question

React Developer — Medium

What is the purpose of the React key prop when reconciling lists, and why is using array index as a key considered problematic?

Accepted Answer

The purpose of the React key prop when reconciling lists is to help React identify which items have changed, are added, or are removed. Using array index as a key is problematic because it can lead to incorrect component state when items are reordered or removed, as the keys no longer correspond to the same logical items.