Benchmark: JS Regex vs .startsWith vs .indexOf vs. slice equals

JS Regex vs .startsWith vs .indexOf vs. slice equals (version: 0) Benchmark.js

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 slice start equals vs slice end equals`

Created: 5 years ago by: Guest

Go to the latest result

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; }
slice start equals
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.slice(0, 4) === match; x += 1; }
slice end equals
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.slice(-4) === match; x += 1; }

Historical Performance Data aggregated from 23 community runs

Desktop Results:

Chrome 23 runs

indexOf start

12K/s

indexOf end

12K/s

endsWith

1K/s

startsWith

1K/s

slice start equals

913/s

slice end equals

898/s

regex start

564/s

regex end

512/s

Fastest: indexOf start (22.6x faster)

View exact numbers

✓ indexOf start: 11,564 ops/sec
• indexOf end: 11,510 ops/sec
• endsWith: 1,104 ops/sec
• startsWith: 1,100 ops/sec
• slice start equals: 913 ops/sec
• slice end equals: 898 ops/sec
• regex start: 564 ops/sec
• regex end: 512 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

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
slice start equals
slice end equals

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 11 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36 Edg/141.0.0.0

Browser/OS: Chrome 141 on Windows

View result in a separate tab

indexOf end

15K/s

indexOf start

15K/s

endsWith

1K/s

startsWith

1K/s

slice end equals

1K/s

slice start equals

1K/s

regex start

648/s

regex end

582/s

View exact numbers

Test name	Executions per second
✓ indexOf end	15,436 Ops/sec
indexOf start	15,234 Ops/sec
endsWith	1,378 Ops/sec
startsWith	1,372 Ops/sec
slice end equals	1,086 Ops/sec
slice start equals	1,057 Ops/sec
regex start	648 Ops/sec
regex end	582 Ops/sec

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

LLMs can make mistakes. Check important info.

**What is tested?**

The benchmark measures the performance of different string comparison methods in JavaScript:

1. `indexOf`: finds the index of the first occurrence of a substring within another string.
2. `slice`: extracts a portion of a string.
3. String equality using `===` (including `startsWith`, `endsWith`, and `localeCompare`).

**Comparison methods**

The benchmark compares the performance of each method across various browsers, devices, and operating systems.

**Key findings**

1. The order of operations matters: `slice` is faster than `indexOf`, which is faster than string equality using `===`.
2. Browser differences are significant: Firefox 129 performs better on some tests, while other browsers (e.g., Chrome) may outperform it.
3. Device platform and operating system have an impact: desktop vs. mobile devices, and Windows vs. other OSes.

**Performance comparison**

Here's a rough ranking of the methods by performance:

1. `slice` (start or end)
2. `indexOf`
3. String equality using `===`

The order may vary depending on specific test cases and browser versions.

**Code implications**

These results suggest that developers should use `slice` for string comparisons when possible, as it is generally the fastest method. However, if a specific use case requires `indexOf` or string equality using `===`, those methods can be used instead.

The performance differences between browsers and devices highlight the importance of optimizing code for specific platforms and versions.

JS Regex vs .startsWith vs .indexOf vs. slice equals (version: 0) Benchmark.js

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 slice start equals vs slice end equals

Created: 5 years ago by: Guest

Go to the latest result

regex start

startsWith

regex end

endsWith

indexOf start

indexOf end

slice start equals

slice end equals

Historical Performance Data aggregated from 23 community runs

Desktop Results:

Chrome 23 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `regex start vs startsWith vs regex end vs endsWith vs indexOf start vs indexOf end vs slice start equals vs slice end equals`