Run results for: JavaScript String Starts/Ends With String Comparisons - Playground

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser: Chrome 122

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

indexOf at end of sentence v1

4K/s

indexOf at end of sentence v2

4K/s

indexOf starts with

4K/s

string endsWith

124/s

string startsWith

124/s

Regex match ends with

123/s

Regex match starts with

121/s

search starts with

42/s

View exact numbers

Test name	Executions per second
✓ indexOf at end of sentence v1	3,972 Ops/sec
indexOf at end of sentence v2	3,955 Ops/sec
indexOf starts with	3,927 Ops/sec
string endsWith	124 Ops/sec
string startsWith	124 Ops/sec
Regex match ends with	123 Ops/sec
Regex match starts with	121 Ops/sec
search starts with	42 Ops/sec

HTML Preparation code:

<div></div>

Script Preparation code:

const iterationNum = 250000;
const possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";
const possibleLen = possible.length;

function getRandomIntInclusive(max, min = 1) {
  const minCeiled = Math.ceil(min);
  const maxFloored = Math.floor(max);
  return Math.floor(Math.random() * (maxFloored - minCeiled + 1) + minCeiled); // The maximum is inclusive and the minimum is inclusive
}

function makeRandomString(len, defaultWord = '') {
  let text = defaultWord;
  for(let i = 0; i < len; i++) {
    text += possible.charAt(getRandomIntInclusive(possibleLen, 0));
  }
  return text + defaultWord;
}

const testWord = window.testWord = makeRandomString(getRandomIntInclusive(10));
const allStrings = window.allStrings = new Array(iterationNum);
const numberOfStrings = window.numberOfStrings = iterationNum;

for(let i = 0; i < numberOfStrings; i++) {
    allStrings[i] = makeRandomString(getRandomIntInclusive(20), testWord);
}

Tests:

indexOf at end of sentence v1
let x = 0; const numberOfStrings = window.numberOfStrings; const allStrings = window.allStrings; const testWord = window.testWord; const testWordLen = testWord.length; while (x < numberOfStrings) { const str = allStrings[x]; str.indexOf(testWord) === str.length - testWordLen; x += 1; }
indexOf at end of sentence v2
let x = 0; const numberOfStrings = window.numberOfStrings; const allStrings = window.allStrings; const testWord = window.testWord; const testWordLen = testWord.length; while (x < numberOfStrings) { const str = allStrings[x]; str.length - str.indexOf(testWord) !== str.length + 1; x += 1; }
string endsWith
let x = 0; const numberOfStrings = window.numberOfStrings; const allStrings = window.allStrings; const testWord = window.testWord; while (x < numberOfStrings) { const str = allStrings[x]; str.endsWith(testWord); x += 1; }
Regex match ends with
let x = 0; const numberOfStrings = window.numberOfStrings; const allStrings = window.allStrings; const testWord = window.testWord; const testWordRegExp = new RegExp(`${testWord}$`); while (x < numberOfStrings) { const str = allStrings[x]; str.match(testWordRegExp); x += 1; }
indexOf starts with
let x = 0; const numberOfStrings = window.numberOfStrings; const allStrings = window.allStrings; const testWord = window.testWord; const testWordLen = testWord.length; while (x < numberOfStrings) { const str = allStrings[x]; str.indexOf(testWord) === 0; x += 1; }
search starts with
let x = 0; const numberOfStrings = window.numberOfStrings; const allStrings = window.allStrings; const testWord = window.testWord; const testWordLen = testWord.length; while (x < numberOfStrings) { const str = allStrings[x]; str.search(testWord) === 0; x += 1; }
string startsWith
let x = 0; const numberOfStrings = window.numberOfStrings; const allStrings = window.allStrings; const testWord = window.testWord; while (x < numberOfStrings) { const str = allStrings[x]; str.startsWith(testWord); x += 1; }
Regex match starts with
let x = 0; const numberOfStrings = window.numberOfStrings; const allStrings = window.allStrings; const testWord = window.testWord; const testWordRegExp = new RegExp(`^${testWord}`); while (x < numberOfStrings) { const str = allStrings[x]; str.match(testWordRegExp); x += 1; }