Benchmark: JS Regex vs .startsWith vs .indexOf vs endsWith vs charAt vs substring

JS Regex vs .startsWith vs .indexOf vs endsWith vs charAt vs substring (version: 0)

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

Comparing performance of: regex start vs startsWith vs regex end vs endsWith vs indexOf start vs indexOf end vs charAt end vs charCodeAt end vs charCodeAt start vs substring

Created: 4 years ago by: Guest

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HTML Preparation code:

<div></div>

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(30)));
}

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; }
substring
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.substring(0, match.length) == match x += 1; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regex start
startsWith
regex end
endsWith
indexOf start
indexOf end
charAt end
charCodeAt end
charCodeAt start
substring

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36

Browser/OS: Chrome 142 on Linux

View result in a separate tab

Test name	Executions per second
regex start	561.8 Ops/sec
startsWith	1281.7 Ops/sec
regex end	521.1 Ops/sec
endsWith	1051.7 Ops/sec
indexOf start	11765.9 Ops/sec
indexOf end	12022.0 Ops/sec
charAt end	870.2 Ops/sec
charCodeAt end	926.3 Ops/sec
charCodeAt start	1076.9 Ops/sec
substring	12229.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

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