Node.js · Senior · Question 65 of 75

How do idempotency keys make POST requests safe to retry?

✓Correct answer: The client sends a unique key; the server stores the result for that key and returns it for repeats instead of doing the work again
2The server rejects all repeated requests with 409
3They make POST work like GET

Explanation

Store the key with the request hash and the response, and handle concurrent requests with the same key (for example, with a lock).

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