Run results for: Regex vs indexOf+substring

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36

Browser: Chrome 109

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
using regexp	1168963.0 Ops/sec
using indexOf + substring	1596320.0 Ops/sec
using split + join	1085018.0 Ops/sec

Script Preparation code:

string = "some string with values in it and other value and many more values and we want to replace some strings in it"
const replace = { 'value': 'X', 'and': 'or', 'string': 'number' }
const expected = 'some number with Xs in it or other X or many more Xs or we want to replace some numbers in it'

const re = /value|and|string/g
const re_replace = (s) => replace[s]
re_replace_all = (input) => input.replace(re, re_replace)

s_replace_all = (input) => {
  let result = input
  for (let from in replace) {
    result = s_replace(result, from, replace[from])
  }
  return result
}

const s_replace = (input, from, to) => {
  let start = ''
  let end = input
  let index = end.indexOf(from)
  while (index !== -1) {
    start += end.substring(0, index) + to
    end = end.substring(index + from.length)
    index = end.indexOf(from)
  }
  return start + end
}

s_replace_all2 = (input) => {
  let result = input
  for (let from in replace) {
    result = result.split(from).join(replace[from])
  }
  return result
}


const assertEqual = (x, y) => {
  if (x !== y) throw new Error('nope')
}
assertEqual(re_replace_all(string), expected)
assertEqual(s_replace_all(string), expected)
assertEqual(s_replace_all2(string), expected)

Tests:

using regexp
re_replace_all(string)
using indexOf + substring
s_replace_all(string)
using split + join
s_replace_all2(string)

Run results for: Regex vs indexOf+substring

using regexp

using indexOf + substring

using split + join