Run results for: Intl.DateTimeFormat perf.

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36

Browser: Chrome 111

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
old	0.6 Ops/sec
new	68.8 Ops/sec

Tests:

old
for(i=0; i<10000; i++){ formatShortDate(new Date("2020-08-19T23:13:44.514Z"), undefined, false); } function formatShortDate(ts, dflt,timezone) { if (!ts && dflt) return dflt; var tsOptions = { month: "numeric", day: "numeric", hour: "numeric", minute: "numeric", hour12: false }; var d = (ts) ? (new Date(ts)) : (new Date()); if (!timezone ) { tsOptions.timeZone = "UTC"; } var d = new Date(ts); return new Intl.DateTimeFormat("lookup", tsOptions).format(d); }
new
for(i=0; i<10000; i++){ formatShortDate(new Date("2020-08-19T23:13:44.514Z"), undefined, false); } function formatShortDate(ts, dflt, timezone) { if (!ts && dflt) return dflt; const date = new Date(ts); var month, day, hours, minutes, utcDate; if (!timezone) { utcDate = new Date(Date.UTC(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate(), date.getUTCHours(), date.getUTCMinutes(), date.getUTCSeconds())); month = (utcDate.getUTCMonth() + 1).toString().padStart(2, '0'); day = utcDate.getUTCDate().toString().padStart(2, '0'); hours = utcDate.getUTCHours().toString().padStart(2, '0'); minutes = utcDate.getUTCMinutes().toString().padStart(2, '0'); } else { month = (date.getMonth() + 1).toString().padStart(2, '0'); day = date.getDate().toString().padStart(2, '0'); hours = date.getHours().toString().padStart(2, '0'); minutes = date.getMinutes().toString().padStart(2, '0'); } return `${day}/${month} ${hours}:${minutes}`; }