Run results for: Intl.NumberFormat vs toLocalString vs string split & reduce

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.146 Safari/537.36

Browser: Chrome 88

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
toLocalString	11478.6 Ops/sec
Intl.NumberFormat	410866.4 Ops/sec
string split & reduce	1060947.8 Ops/sec

Script Preparation code:

var nf = new Intl.NumberFormat("en-US")

function pricize (num) {
  const pieces = num.toString().split('')
  const len = pieces.length
  return pieces.reduce((result, chr, index, array) => {
    const pos = len - index
    result += (index !== 0 && pos % 3 === 0) ? ',' + chr : chr
    return result
  }, '')
}

Tests:

toLocalString
var a = (10000).toLocaleString("en-US");
Intl.NumberFormat
var a = nf.format(10000)
string split & reduce
var a = pricize(10000)