Run results for: Memoized Intl.NumberFormat vs fresh instances

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 Edg/120.0.0.0

Browser: Chrome 120

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
new Intl.NumberFormat	29132.5 Ops/sec
memoized instance	29199.2 Ops/sec

Script Preparation code:

window.cache = new Map();

window.format = (locale, currency, value) => new Intl.NumberFormat(locale, { style: 'currency', currency }).format(value);

window.memoizedFormat = (locale, currency, value) => {
  const key = [locale, currency];
  let formatter = window.cache.get(key);
  
  if (!formatter) {
    formatter = new Intl.NumberFormat(locale, { style: 'currency', currency });
    window.cache.set(key, formatter);
  }
  
  return formatter.format(value);
};

Tests:

new Intl.NumberFormat
window.format('pt-BR', 'BRL', 100_346_999.21);
memoized instance
window.memoizedFormat('pt-BR', 'BRL', 100_346_999.21);

Run results for: Memoized Intl.NumberFormat vs fresh instances

new Intl.NumberFormat

memoized instance