Grokking Node.js Design Patterns for Interviews/

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Solution: Add Logging to a Utility Function

Solution: Add Logging to a Utility Function

Wrap a pure function with a logging decorator that prints input and output, without touching the original logic.

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Solution explanation

  • Lines 1–3: square(n) is a pure utility function that simply returns n * n. It’s untouched and unaware of logging.

  • Lines 6–13: withLogging(fn) is a functional decorator. It wraps the original function:

    • Logs the arguments before calling fn(...). ...