Run results for: Intl.DateTimeFormat vs Date().toLocaleString()

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser: Chrome 135

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
Date().toLocaleString	31418.9 Ops/sec
Intl.DateTimeFormat	30003.8 Ops/sec

Script Preparation code:

var options = {
  year: 'numeric', month: 'numeric', day: 'numeric',
  hour: 'numeric', minute: 'numeric', second: 'numeric',
  hour12: false,
  fractionalSecondDigits: 3,
}

Tests:

Date().toLocaleString
new Date().toLocaleString("en-US", options)
Intl.DateTimeFormat
new Intl.DateTimeFormat('en-US', options).format(new Date())