30-seconds-of-code/snippets/js/s/hz.md

title, type, language, tags, unlisted, cover, dateModified

title	type	language	tags	unlisted	cover	dateModified
Hertz frequency of function	snippet	javascript	function	true	stairs-from-below	2021-01-04T13:04:15+02:00

Measures the number of times a function is executed per second (hz/hertz).

• Use performance.now() to get the difference in milliseconds before and after the iteration loop to calculate the time elapsed executing the function iterations times.
• Return the number of cycles per second by converting milliseconds to seconds and dividing it by the time elapsed.
• Omit the second argument, iterations, to use the default of 100 iterations.

const hz = (fn, iterations = 100) => {
  const before = performance.now();
  for (let i = 0; i < iterations; i++) fn();
  return (1000 * iterations) / (performance.now() - before);
};

const numbers = Array(10000).fill().map((_, i) => i);

const sumReduce = () => numbers.reduce((acc, n) => acc + n, 0);
const sumForLoop = () => {
  let sum = 0;
  for (let i = 0; i < numbers.length; i++) sum += numbers[i];
  return sum;
};

Math.round(hz(sumReduce)); // 572
Math.round(hz(sumForLoop)); // 4784