Run results for: JavaScript: Regex vs .startsWith vs .indexOf

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser: Chrome 131

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Regex start

483/s

Regex end

442/s

startsWith

122/s

endsWith

121/s

indexOf start

108/s

indexOf end

61/s

View exact numbers

Test name	Executions per second
✓ Regex start	483 Ops/sec
Regex end	442 Ops/sec
startsWith	122 Ops/sec
endsWith	121 Ops/sec
indexOf start	108 Ops/sec
indexOf end	61 Ops/sec

HTML Preparation code:

<div></div>

Script Preparation code:

window.match = 'test';
window.matchLength = window.match.length;
var data = window.data = [];
const possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
var TOTAL_STRINGS = window.TOTAL_STRINGS = 100000;

function getRandomInt(max) {
  return Math.floor(Math.random() * max);
}

function makeRandomString(len) {
  var text = "";
  for( var i=0; i < len; i++ ) {
    text += possible.charAt(getRandomInt(possible.length));
  }
  return text;
}

while (data.length < TOTAL_STRINGS) {
  data.push(makeRandomString(getRandomInt(20)));
}

Tests:

startsWith
window.data.forEach(str => str.startsWith(window.match));
endsWith
window.data.forEach(str => str.endsWith(window.match));
Regex start
var regex = /^test/; window.data.forEach(str => regex.test(str));
Regex end
var regex = /test$/; window.data.forEach(str => regex.test(str));
indexOf start
window.data.forEach(str => str.indexOf(window.match) === 0);
indexOf end
window.data.forEach(str => str.indexOf(window.match) === str.length - window.matchLength);