[Solved] What will be the output of this interceptor code snippet when the controller returns { data: 5 }?intercept(context, next) { return next.handle().pipe(map(data => ({ ...data, extra: 10 }))); } | NestJS

NestJS - Interceptors

What will be the output of this interceptor code snippet when the controller returns { data: 5 }?

intercept(context, next) {
  return next.handle().pipe(map(data => ({ ...data, extra: 10 })));
}

AError: map is not a function

B{ data: 5, extra: 10 }

C{ extra: 10 }

D{ data: 5 }

Step-by-Step Solution

Solution:

Step 1: Understand the interceptor modifies response
The interceptor uses map to add an extra property to the original data object.
Step 2: Apply the map transformation
The original { data: 5 } is spread and extra: 10 is added, resulting in { data: 5, extra: 10 }.
Final Answer:
{ data: 5, extra: 10 } -> Option B
Quick Check:
map adds extra property = { data: 5, extra: 10 } [OK]

Quick Trick: map merges new properties into response object [OK]

Common Mistakes:

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What will be the output of this interceptor code snippet when the controller returns { data: 5 }?