Bench2.js

function memoize(fn) {
  return function() {
    var args = Array.prototype.slice.call(arguments);
    fn.cache = fn.cache || {};
    return fn.cache[args]
      ? fn.cache[args]
      : (fn.cache[args] = fn.apply(this, args));
  };
}

function sqrt(arg) {
  let result = 0.0;
  for (let i = 0; i < 1000000; i += 1) result += Math.sqrt(arg);
  return result;
}

const memoizedSqrt = memoize(sqrt);

console.time('memoized call');
memoizedSqrt(4);
console.timeEnd('memoized call'); // 10.461ms

console.time('non-memoized call');
memoizedSqrt(4);
console.timeEnd('non-memoized call'); // 0.022ms

console.time('Direct call');
sqrt(4);
console.timeEnd('Direct call'); // 6.855ms