Run results for: Intl.DateTimeFormat (optimized) vs new Date().toLocaleDateString()

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0

Browser: Firefox 78

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
new Date()	407403.2 Ops/sec
Intl.DateTimeFormat()	237681.5 Ops/sec
Date().toLocaleString()	3723.6 Ops/sec
JavaScript Date Time format	981195.1 Ops/sec
JavaScript Date Time format using Template Strings.	1023746.6 Ops/sec

Script Preparation code:

var options = {
  year: 'numeric', month: 'numeric', day: 'numeric',
  hour: 'numeric', minute: 'numeric', second: 'numeric',
  hour12: false,
  fractionalSecondDigits: 3,
}
var intlFormat = new Intl.DateTimeFormat('en-US', options);

Tests:

new Date()
(new Date()).toISOString().trim().replace('T', ' ').replace('Z', '')
Intl.DateTimeFormat()
intlFormat.format(new Date())
Date().toLocaleString()
new Date().toLocaleString("en-US", options)
JavaScript Date Time format
let date_time = new Date() let formatted_date = date_time.getFullYear() + "-" + (date_time.getMonth() + 1) + "-" + date_time.getDate() + " " + date_time.getHours() + ":" + date_time.getMinutes() + ":" + date_time.getSeconds() + "." + date_time.getMilliseconds()
JavaScript Date Time format using Template Strings.
let date_time = new Date() let formatted_date = `${date_time.getFullYear()}-${date_time.getMonth() + 1}-${date_time.getDate()} ${date_time.getHours()}:${date_time.getMinutes()}:${date_time.getSeconds()}.${date_time.getMilliseconds()}`

Run results for: Intl.DateTimeFormat (optimized) vs new Date().toLocaleDateString()

new Date()

Intl.DateTimeFormat()

Date().toLocaleString()

JavaScript Date Time format

JavaScript Date Time format using Template Strings.