Run results for: parseDateISO vs parseDate vs parseDateInline

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36

Browser: Chrome 127

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

new Date

4.4M/s

parseDateInline

3.8M/s

parseDateISO

3.8M/s

parseDate

3.4M/s

View exact numbers

Test name	Executions per second
✓ new Date	4,364,060 Ops/sec
parseDateInline	3,798,112 Ops/sec
parseDateISO	3,776,009 Ops/sec
parseDate	3,387,259 Ops/sec

Script Preparation code:

var dateTimeISO = '2024-08-21T17:00:00.000Z'

var normalizeToLocalDate = (date) =>
    date.length === 10 && /^\d{4}-\d{2}-\d{2}$/.test(date) ? ` ${date}` : date;

var parseDateISO = (date) => new Date(date);

var parseDate = (date) => new Date(normalizeToLocalDate(date));

var parseDateInline = (date) =>
    date.length === 10 && /^\d{4}-\d{2}-\d{2}$/.test(date) ?
    new Date(` ${date}`) :
    new Date(date);

Tests:

new Date
new Date(dateTimeISO)
parseDateISO
parseDateISO(dateTimeISO)
parseDate
parseDate(dateTimeISO)
parseDateInline
parseDateInline(dateTimeISO)