react列表key滿足這些條件可以直接使用數組索引

1. the list and items are static–they are not computed and do not change;
2. the items in the list have no ids;
3. the list is never reordered or filtered.

When all of them are met, you may safely use the index as a key.

 

參考：Index as a key is an anti-pattern (React) | by Robin Pokorny | Medium