Add no-array-index-key to recommended configuration

This rule prevents the use of Array index in key. It seems useful enough to turn on as a recommended rule. Thoughts?

[jeffvandyke]

It’s WAY too strong of a rule, IMO. I’ve got an array of strings, how can I possibly concisely display it in a list of

's without using index as the key? It’s simply the cleanest way to do it without React throwing a warning.

I still can’t think of how you could determine if a component is “simple enough” to not have a useful id field. That would be best, if possible, but I don’t think it is.

[jeffvandyke]

As a matter of fact, at the bottom of the Keys section in React docs, it explicitly says: “When you don’t have stable IDs for rendered items, you may use the item index as a key as a last resort”. For my use case above, which is not rare, what better alternative is there?