String replace comparison

function timeIt(f) {
  const t0 = Date.now()
  const r = f()
  const t1 = Date.now()
  return t1-t0
}

function randomString(length) {
  let str = '';
  const chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890. '
  for(i = 0; i < length; i++) {
    const c = Math.floor(Math.random() * chars.length)
    str += chars[c]
  }
  return str
}

function replaceRegex(str) {
  return str.replace(/[aeiou]/gi, '')
}

function replace(str) {
  const vowels = ['a','e','i','o','u','A','E','I','O','U']
  let newStr = '';
  for(i = 0; i < str.length; i++) {
    let c = str.charAt(i)
    if (vowels.indexOf(c) === -1) {
      newStr += c
    }
  }
  return newStr
}

function iterate(count, length, f) {
  let time = 0
  for(let i = 0; i < count; i++) {
    testStr = randomString(length)
    time += timeIt(() => f(testStr))
  }
  return time
}

function compare(count, length, f1, f2) {
  console.log('f1: ', iterate(count, length, f1))
  console.log('f2: ', iterate(count, length, f2))
}

function testSame() {
  const s = randomString(10)
  console.log(s)
  if (replace(s) !== replaceRegex(s)) {
    console.error('Result differ!')
  }
}

testSame()
compare(10000, 10000, replaceRegex, replace)