[Solved] Consider this LoggingInterceptor snippet:intercept(context: ExecutionContext, next: CallHandler): Observable { const start = Date.now(); return next.... }What will be logged when a request completes? | NestJS

NestJS - Interceptors

Consider this LoggingInterceptor snippet:

intercept(context: ExecutionContext, next: CallHandler): Observable {
  const start = Date.now();
  return next.handle().pipe(
    tap(() => console.log(`Processed in ${Date.now() - start}ms`))
  );
}

What will be logged when a request completes?

ANo output will be logged

BThe request URL and method

COnly the start timestamp

DThe time in milliseconds it took to process the request

Step-by-Step Solution

Solution:

Step 1: Analyze the code
The interceptor records the start time before calling next.handle().
Step 2: Understand tap operator
tap logs the difference between current time and start time after the request completes.
Final Answer:
The time in milliseconds it took to process the request -> Option D
Quick Check:
Logs duration, not URL or method. [OK]

Quick Trick: tap logs after observable completes, showing duration [OK]

Common Mistakes:

Expecting URL or method to be logged without explicit code
Thinking tap logs before request completion

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More NestJS Quizzes

Consider this LoggingInterceptor snippet:

Step 1: Analyze the code

Step 2: Understand tap operator

Final Answer:

Quick Check:

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