Run results for: toISOString vs concat

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/113.0

Browser: Firefox 113

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
toISOString	2989.7 Ops/sec
concat	6907.3 Ops/sec

Script Preparation code:

var date = new Date();

function toISOString(date) {
	return date.toISOString().substr(0, 10);
}

function concat(date) {
 	var d = date.getDate();
	var m = date.getMonth() + 1;
	var y = date.getFullYear();
    var day = d <= 9 ? '0' + d : '' + d;
    var month = m <= 9 ? '0' + m : '' + m;
    var year = '' + y;
	return day + '-' + month + '-' + year;
}

Tests:

toISOString
for (var i=0; i<1000; ++i) { toISOString(date); }
concat
for (var i=0; i<1000; ++i) { concat(date); }