Benchmark: Regex vs endsWith vs indexOf vs lastIndexOf

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
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; }
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
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; }
lastindexof
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.lastIndexOf(match) === str.length - length; x += 1; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Regex
endswith
indexof
lastindexof

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36 OPR/116.0.0.0

Browser/OS: Opera 116 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Regex	402.5 Ops/sec
endswith	975.7 Ops/sec
indexof	12048.6 Ops/sec
lastindexof	252.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and their pros and cons.

**Benchmark Overview**

The provided benchmark compares four string manipulation methods in JavaScript:

1. `Regex`
2. `endsWith`
3. `indexOf`
4. `lastIndexOf`

Each method is used to check if a given string (`str`) ends or starts with a specific pattern (`match`).

**Test Case Analysis**

Here's a brief analysis of each test case:

* **Regex**: This test uses the `test()` method to search for the first occurrence of the regular expression in the input string.
* **endsWith**: This test checks if the input string ends with the specified pattern using the `endsWith()` method.
* **indexOf**: This test searches for the first occurrence of the specified pattern in the input string using the `indexOf()` method.
* **lastIndexOf**: This test finds the last occurrence of the specified pattern in the input string using the `lastIndexOf()` method.

**Library and Special JS Feature**

The provided benchmark uses a custom library to generate random strings. The library is not explicitly named, but it's used to create an array of strings (`data`) with varying lengths. This allows for large-scale testing of each method.

No special JavaScript features or syntax are mentioned in the test cases. However, note that some browsers may have specific optimizations or limitations when using certain string manipulation methods (e.g., `Regex`).

**Comparison and Pros/Cons**

Here's a brief comparison of the four methods:

* **Regex**: Fast, but can be slow for large strings due to backtracking.
	+ Pros: High performance, flexible pattern matching.
	+ Cons: Can be complex, slower for very large strings.
* **endsWith**: Simple and efficient for checking if a string ends with a specific pattern.
	+ Pros: Fast, easy to use.
	+ Cons: Only checks the end of the string; no support for regular expressions.
* **indexOf**: Fast and efficient for searching the first occurrence of a pattern in a string.
	+ Pros: High performance, straightforward usage.
	+ Cons: May return -1 if the pattern is not found, can be slow for very large strings.
* **lastIndexOf**: Similar to `indexOf`, but finds the last occurrence of a pattern instead.
	+ Pros: Fast, easy to use.
	+ Cons: May return -1 if the pattern is not found; slower than `indexOf` for very large strings.

**Other Alternatives**

If you were to implement these benchmarks yourself or explore alternative approaches:

* **Using `String.prototype.includes()`**: Instead of implementing your own string manipulation methods, consider using the `includes()` method, which provides a similar functionality without the need for manual implementation.
* **Using optimized string algorithms**: Depending on the specific use case, more efficient string algorithms like Boyer-Moore or Knuth-Morris-Pratt search may be available for certain platforms or libraries.

Keep in mind that these alternatives might not provide exactly the same results as the original benchmark, but they can offer interesting trade-offs between performance, readability, and implementation complexity.

Related benchmarks:

Regex vs endsWith vs indexOf vs lastIndexOf (version: 0)

Comparing performance of: Regex vs endswith vs indexof vs lastindexof

Created: 3 years ago by: Guest

Jump to the latest result

Regex

endswith

indexof

lastindexof

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):