Run results for: JS Regex vs .startsWith vs .indexOf vs endsWith vs charAt

Test name	Executions per second
✓ indexOf start	9,263 Ops/sec
indexOf end	8,761 Ops/sec
startsWith	710 Ops/sec
endsWith	701 Ops/sec
charCodeAt end	649 Ops/sec
charCodeAt start	635 Ops/sec
charAt end	617 Ops/sec
regex start	407 Ops/sec
regex end	376 Ops/sec

Script Preparation code:

window.regexStart = /^test/;
window.regexEnd = /test$/;
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.regexStart; 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) === 0; x += 1; }
regex end
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var regex = window.regexEnd; while (x < TOTAL_STRINGS) { const str = data[x]; regex.test(str); x += 1; }
endsWith
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.endsWith(match) === 0; 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.indexOf(match) === 0; x += 1; }
indexOf end
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; var length = window.matchLength; while (x < TOTAL_STRINGS) { const str = data[x]; str.indexOf(match) === str.length - length; x += 1; }
charAt end
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; var matchLen = match.length; while (x < TOTAL_STRINGS) { const str = data[x]; if (str && str.length >= matchLen) { let strLen = str.length; for (let i = 1; i <= matchLen; i++) { if (str.charAt(strLen - i) !== match.charAt(matchLen - i)) break; } } x += 1; }
charCodeAt end
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; var matchLen = match.length; while (x < TOTAL_STRINGS) { const str = data[x]; if (str && str.length >= matchLen) { let strLen = str.length; for (let i = 1; i <= matchLen; i++) { if (str.charCodeAt(strLen - i) !== match.charCodeAt(matchLen - i)) break; } } x += 1; }
charCodeAt start
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; var matchLen = match.length; while (x < TOTAL_STRINGS) { const str = data[x]; if (str && str.length >= matchLen) { for (let i = 0; i < matchLen; i++) { if (str.charCodeAt(i) !== match.charCodeAt(i)) break; } } x += 1; }

Run results for: JS Regex vs .startsWith vs .indexOf vs endsWith vs charAt

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

regex start

startsWith

regex end

endsWith

indexOf start

indexOf end

charAt end

charCodeAt end

charCodeAt start