Fibonacci face-off

Fibonacci-faceoff.js

function domsFib(number) {
  let time = new Date();
  let sequence = [1,1]
  for (let i = 2; i<number; i++) {
    let index = (i-1)%2;
    sequence[index] = sequence[0] + sequence[1];
  }
  if (number%2) return sequence[1]
  else return sequence[0]
}

function dadsFib(number) {
  let prev2 = 1;
  let sum = 1;
  for (let i = 2; i < number; i++) {
    let prev1 = sum;
    sum += prev2;
    prev2 = prev1;
  }
  return sum;
}

const dumbFib = number => number < 3 ? 1 : dumbFib(number-1) + dumbFib(number-2);

function memoize(func) {
  let cache = [];
  return x => x in cache ? cache[x] : cache[x] = func(x);
}

let memoFib = memoize(number => number < 3 ? 1 : memoFib(number-1) + memoFib(number-2));
// memoFib.name = "memoFib"; // Doesn't work, not sure why

const oneOffMemoFib = number => {
  let fib = memoize(number => number < 3 ? 1 : fib(number-1) + fib(number-2));
  return fib(number);
}

let funcs = [domsFib, dadsFib, memoFib, oneOffMemoFib].map(func =>
  ({ name: func.name || "memoFib", func })
);

const testResults = (funcs, number) => {
  funcs.forEach(({name, func}) => {
    console.log(`Result for ${name}: ${func(number)}`);
  });
  if (!funcs.every(({func}) => func(number) == funcs[0].func(number))) {
    console.log("Note: the results differ");
  }
}

const benchmark = (func, arg, repetitions) => {
  let startTime = new Date();
  for (let i = 0; i < repetitions; i++) {
    func(arg);
  }
  return (new Date() - startTime) / repetitions;
}

const testEfficiency = (funcs, number, repetitions) => {
  let elapsed = funcs.map(({name, func}) =>
    ({ name, time: benchmark(func, number, repetitions) })
  );
  elapsed.forEach(({name, time}) => {
    const ratio = (time / elapsed[0].time).toFixed(4);
    console.log(`Running time for ${name}: ${time} = ${ratio}x ${elapsed[0].name}`);
  });
}

let useDumb = process.argv.includes("dumb");

const number = useDumb ? 30 : 60;
const reps = useDumb ? 1000 : 1000000;
if (useDumb) funcs.push({name:"dumbFib", func:dumbFib});

testResults(funcs, number);
testEfficiency(funcs, number, reps);

To run this in NodeJS with useDumb set to true, append the word "dumb" to the end of the command line.