Run results for: Intl.NumberFormat vs toLocalString vs string split & reduce (with fraction digits) vs toFixed

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.0 Safari/605.1.15

Browser: Safari 16

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
toLocaleString	21632.4 Ops/sec
Intl.NumberFormat	21090.6 Ops/sec
string split & reduce	1113651.0 Ops/sec
toFixed	5303885.0 Ops/sec

Script Preparation code:

function pricize (num, decimal = 0) {
  const intPart = Math.floor(num)
  const intPieces = intPart.toString().split('')
  const len = intPieces.length
  const intStr = intPieces.reduce((result, chr, index, array) => {
    const pos = len - index
    result += (index !== 0 && pos % 3 === 0) ? ',' + chr : chr
    return result
  }, '')

  const decStr = decimal > 0
    ? num.toFixed(decimal + 1).toString().slice(-(decimal + 2), -1) // toFixed() は四捨五入してしまうので(decimal + 1)桁まで求めて切り取る
    : ''

  return intStr + decStr
}

var target = 123456789.123456789
var options = {minimumFractionDigits: 3, maximumFractionDigits: 3}

Tests:

toLocaleString
var a = target.toLocaleString('en-US', options);
Intl.NumberFormat
var a = new Intl.NumberFormat('en-US', options).format(target)
string split & reduce
var a = pricize(target, 3)
toFixed
var a = target.toFixed(3)

Run results for: Intl.NumberFormat vs toLocalString vs string split & reduce (with fraction digits) vs toFixed

toLocaleString

Intl.NumberFormat

string split & reduce

toFixed