Run results for: JS Regex vs .startsWith vs .indexOf Jan

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.63 Safari/537.36

Browser: Chrome 93

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
regex start	471.8 Ops/sec
startsWith	555.4 Ops/sec
indexOf start	8988.7 Ops/sec
toLowerCase().startsWith	280.8 Ops/sec

HTML Preparation code:

<div></div>

Script Preparation code:

window.regexpStart = new RegExp('^p.*', 'i');
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:

regex start
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var regex = window.regexpStart; while (x < TOTAL_STRINGS) { const str = data[x]; regex.test(str); x += 1; }
startsWith
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; while (x < TOTAL_STRINGS) { const str = data[x]; str.startsWith(match); x += 1; }
indexOf start
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; while (x < TOTAL_STRINGS) { const str = data[x]; str.toLowerCase().indexOf(match) === 0; x += 1; }
toLowerCase().startsWith
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; while (x < TOTAL_STRINGS) { const str = data[x]; str.toLowerCase().startsWith(match); x += 1; }

Run results for: JS Regex vs .startsWith vs .indexOf Jan

fork of https://www.measurethat.net/Benchmarks/Show/975/11/regex-vs-indexof-vs-startswith-vs-substr

regex start

startsWith

indexOf start

toLowerCase().startsWith