Performance of various iterations in AppsScripts

README.md

Performance

Screenshot of result of running main:

Info	forEachIteration_ took 9796 milliseconds
Info	forOfLetIteration_ took 12521 milliseconds
Info	forOfConstIteration_ took 12309 milliseconds

Code.gs

function measure_({func, arr}) {
  const start = new Date().getTime();

  func.call(null, arr);

  const end = new Date().getTime();
  const delta = end - start;
  const report = `${func.name} took ${delta} milliseconds`;
  Logger.log(report);
  return delta;
}

function add100_(v) {
  return v + 10 * v;
}

function perform_(value) {
  for (let x = value; x >= 0; x--) {
    // just do some math that is complex enough to take some time
    const y = x * 100 / 3293.332 - (32);
    const b = 100 - add100_(y);
  }
}

function forOfConstIteration_ (arr) {
  for (const value of arr) {
    perform_(value);
  }
}

function forOfLetIteration_ (arr) {
  for (let value of arr) {
    perform_(value);
  }
}

function forEachIteration_ (arr) {
  arr.forEach(perform_);
}

function main () {
  const length = 100000;
  const arr = [...Array.from({length}).keys()];
  const funcs = [forEachIteration_, forOfLetIteration_, forOfConstIteration_];
  for (const func of funcs) {
    measure_({func, arr});
  }
}