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Consider this Node.js code snippet debugged in VS Code with a breakpoint on line 3:

medium📝 component behavior Q13 of 15
Node.js - Debugging and Profiling
Consider this Node.js code snippet debugged in VS Code with a breakpoint on line 3:
1 const x = 5;
2 const y = 10;
3 const sum = x + y;
4 console.log(sum);

When paused at the breakpoint on line 3, what will be the value of sum in the debugger?
Aundefined
B15
C5
DError: sum is not defined
Step-by-Step Solution
Solution:

  1. Step 1: Understand when the breakpoint pauses execution

    The breakpoint on line 3 pauses before executing that line, so sum is not yet assigned.

  2. Step 2: Determine the value of sum at pause

    Since line 3 hasn't run, sum is declared but not assigned, so its value is undefined.

  3. Final Answer:

    undefined -> Option A

  4. Quick Check:

    Breakpoint pauses before assignment, sum = undefined [OK]
Quick Trick: Breakpoint pauses before line runs, variable not assigned yet [OK]
Common Mistakes:
  • Assuming sum already has the calculated value
  • Confusing declaration with assignment timing
  • Expecting runtime error at breakpoint

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