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JavaScript React by Example Building the Application Creating the Counter

Anthony Albertorio
Anthony Albertorio
22,169 Points

Why not use .filter() instead of .reduce() for getAttendingGuests()?

Why not use simpler code?

  getAttendingGuests = () =>
    this.state.guests.filter( guest => guest.isConfirmed).length;

1 Answer

Steven Parker
Steven Parker
210,867 Points

The code might be a bit more compact, but I'd expect that the "reduce" version is more efficient. Try them both in a benchmarking tool and see!.

Anthony Albertorio
Anthony Albertorio
22,169 Points

How would I be able to do that? Any suggestions?

Steven Parker
Steven Parker
210,867 Points

There are a number of online benchmarking and comparison tools around. I was curious to see if my guess was correct so I tried it myself over at JS Bench.

It said the original (reduce) version is five times faster than doing it with filter.