Benchmark: JS Regex vs .startsWith vs .indexOf vs .includes

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(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.startsWith(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; }
includes
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.includes(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
includes

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Linux; Android 11; Redmi Note 9 Pro) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 104 on Android

View result in a separate tab

Test name	Executions per second
regex start	222.6 Ops/sec
startsWith	209.4 Ops/sec
regex end	214.2 Ops/sec
endsWith	208.1 Ops/sec
indexOf start	2763.3 Ops/sec
indexOf end	2802.9 Ops/sec
includes	2807.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**What is being tested?**

The provided JSON represents a benchmark test comparing the performance of four different string matching methods in JavaScript:

1. `String.prototype.indexOf()`: searches for a specified value (in this case, the match) from the start of a string.
2. `String.prototype.includes()`: searches for a specified value (in this case, the match) anywhere in a string.
3. `RegExp.prototype.test()`: tests whether a regular expression matches a specified value (in this case, the match).
4. `String.prototype.startsWith()` and `String.prototype.endsWith()`: test whether a string starts or ends with a specified value (in this case, the match).

**Options compared**

The benchmark compares the performance of each method:

* `indexOf` is tested on strings starting from different positions.
* `includes` is tested on strings of varying lengths.
* `test` is used with regular expressions and literal values.
* `startsWith` and `endsWith` are tested on strings with prefixes and suffixes.

**Why these methods?**

The choice of methods likely aims to showcase:

1. `indexOf`: a fundamental string matching method that's widely used in JavaScript.
2. `includes`: a more modern method introduced in ECMAScript 2015, which is gaining popularity for its simplicity and efficiency.
3. `test` with regular expressions: a powerful tool for pattern matching, but potentially slower due to the complexity of regex engines.
4. `startsWith` and `endsWith`: string methods that are often used together, making their performance worth comparing.

**Benchmarks results**

The latest benchmark results show that:

* `includes` performs the best among all methods, followed closely by `indexOf`.
* `test` with regular expressions is significantly slower than the other methods.
* `startsWith` and `endsWith` are relatively fast, but still outperformed by `includes`.

**Device and browser**

The test was conducted on a Chrome Mobile 104 device running Android 11.

Keep in mind that these results might vary depending on your specific environment, JavaScript engine, and hardware. The benchmark serves as a general guideline for the relative performance of each method.

Related benchmarks:

JS Regex vs .startsWith vs .indexOf vs .includes (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 includes

Created: 2 years ago by: Guest

Jump to the latest result

regex start

startsWith

regex end

endsWith

indexOf start

indexOf end

includes

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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