Run results for: Rounding methods

Run details:

User agent: Mozilla/5.0 (Android 4.4.2; Tablet; rv:68.0) Gecko/68.0 Firefox/68.0

Browser: Android 4

Operating system: Android 4.4.2

Device Platform: Tablet

Date tested: 5 years ago

Test name	Executions per second
Simple rounding	10991604.0 Ops/sec
Rounding with epsilon and string conversion	184544.5 Ops/sec
Rounding with "if" statement	5203109.5 Ops/sec
Rounding by toLocaleString	954.4 Ops/sec

Script Preparation code:

function round2(num, places) {
  return +(Math.round(num + "e+" + places)  + "e-" + places);
}

function round3(num, places) {
  if (places === 2) { 
    return Math.round( Math.round( num * 1000 ) / 10 ) / 100
  } else {
    const multiplier = Math.pow(10, places)
  	return Math.round(num * multiplier) / multiplier
  }
}

function round4(num, places) {
  +(num.toLocaleString(
    'en', 
    { maximumFractionDigits: places, useGrouping: false }
  ))
}

Tests:

Simple rounding
Math.round(12.345 * 100) / 100
Rounding with epsilon and string conversion
round2(12.345, 2)
Rounding with "if" statement
round3(12.345, 2)
Rounding by toLocaleString
round4(12.345, 2)

Run results for: Rounding methods

First test is incorrect but needed to evaluate the performance penalty

Simple rounding

Rounding with epsilon and string conversion

Rounding with "if" statement

Rounding by toLocaleString