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Why does the error-first callback convention use null instead of undefined for no error?

hard📝 Conceptual Q10 of 15
Node.js - Error Handling Patterns
Why does the error-first callback convention use null instead of undefined for no error?
AUndefined is reserved for data values
BUndefined causes the callback to fail
CNull is faster to check than undefined
DNull explicitly means no error, avoiding ambiguity with undefined
Step-by-Step Solution
Solution:

  1. Step 1: Understand difference between null and undefined

    Null is an explicit value meaning 'no value', undefined means 'not assigned'.

  2. Step 2: Reason why null is preferred for no error

    Using null avoids confusion and clearly signals no error occurred.

  3. Final Answer:

    Null explicitly means no error, avoiding ambiguity with undefined -> Option D

  4. Quick Check:

    Null signals no error clearly [OK]
Quick Trick: Use null to clearly indicate no error [OK]
Common Mistakes:
  • Using undefined and causing ambiguity
  • Assuming undefined means no error
  • Believing null is slower than undefined

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