You want to log request time using functional middleware and then pass control. Which code correctly measures and logs the time taken by the next middleware or handler?

hard📝 Application Q9 of 15

NestJS - Middleware

Afunction timer(req, res, next) { console.log('Timer started'); }

Bfunction timer(req, res, next) { const start = Date.now(); console.log(`Time: ${Date.now() - start}ms`); next(); }

Cfunction timer(req, res, next) { const start = Date.now(); next(); const end = Date.now(); console.log(`Time: ${end - start}ms`); }

Dfunction timer(req, res, next) { next(); console.log('Timer started'); }

Step-by-Step Solution

Solution:

Step 1: Measure time before and after next()
Start time is recorded before calling next(), end time after next() returns.
Step 2: Calculate and log elapsed time
Subtract start from end to get duration, then log it.
Final Answer:
function timer(req, res, next) { const start = Date.now(); next(); const end = Date.now(); console.log(`Time: ${end - start}ms`); } -> Option C
Quick Check:
Log time after next() returns [OK]

Quick Trick: Record start before next(), log after next() [OK]

Common Mistakes:

Logging time before calling next()
Not calling next() at all
Logging static messages without timing

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You want to log request time using functional middleware and then pass control. Which code correctly measures and logs the time taken by the next middleware or handler?

Step 1: Measure time before and after next()

Step 2: Calculate and log elapsed time

Final Answer:

Quick Check:

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