JavaScript · Middle · Question 67 of 75

What does `options.onSuccess?.(data)` do?

✓Correct answer: Calls onSuccess only if it exists; otherwise returns undefined without an error
2Always calls onSuccess
3Checks whether data is defined

Explanation

Optional call syntax is handy for optional callbacks. It still throws if onSuccess exists but isn't a function.

Further reading

javascript.info: Optional chaining ?. ↗

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