Benchmark: string.replace vs regexp.matchAll vs regexp.exec

Tests:

string.replace
const s = 'Apple Apple Apple Apple Apple'; const r = new RegExp('(^|\\P{L})(Apple)($|\\P{L})', 'giu'); s.replace(r, '*****');
regexp.matchAll
const s = 'Apple Apple Apple Apple Apple'; const r = new RegExp('(^|\\P{L})(Apple)($|\\P{L})', 'giu'); const n = []; const matches = [...s.matchAll(r)]; matches.forEach((match) => { // do something // n.push(match.index); });
regexp.exec
const s = 'Apple Apple Apple Apple Apple'; const r = new RegExp('(^|\\P{L})(Apple)($|\\P{L})', 'giu'); const n = []; let execResults; while ((execResults = r.exec(s)) !== null) { // do something // n.push(execResults.index); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
string.replace
regexp.matchAll
regexp.exec

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36

Browser/OS: Chrome 134 on Windows

View result in a separate tab

Test name	Executions per second
string.replace	4464464.0 Ops/sec
regexp.matchAll	1400121.5 Ops/sec
regexp.exec	2547809.5 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 is being tested, compared, and their pros and cons.

**Benchmark Overview**

The test cases compare three different approaches for processing strings: `string.replace`, `regexp.matchAll`, and `regexp.exec`. The goal is to determine which approach is fastest.

**Options Compared**

1. **string.replace**: This method replaces occurrences of a pattern in a string.
2. **regexp.matchAll**: This method returns all matches of a regular expression in a string.
3. **regexp.exec**: This method executes the regex engine on a given string, returning a match array.

**Pros and Cons**

* `string.replace`:
	+ Pros: Simple to use, efficient for simple replacements.
	+ Cons: Can be slow for complex patterns or large strings.
* `regexp.matchAll`:
	+ Pros: Returns all matches, can be useful for finding multiple occurrences.
	+ Cons: May consume more memory and CPU resources than other methods.
* `regexp.exec`:
	+ Pros: Efficient for iterating over a string and finding matches one by one.
	+ Cons: Requires manual looping to iterate over matches.

**Library**

In the test cases, the regular expression library used is built-in JavaScript's `RegExp`. This is because it's part of the standard JavaScript specification.

**Special JS Feature or Syntax**

There are no special JavaScript features or syntax used in these benchmark tests. However, there are some notable features of the regex engine:

* The regular expression pattern uses `\P{L}` to match non-lowercase letters.
* The `giu` flags at the end of the pattern enable case-insensitive matching and Unicode properties.

**Benchmark Preparation Code**

The preparation code is empty for all test cases, which means that the benchmarks start with a clean slate. This is good because it allows each approach to be tested in isolation without any overhead from previous runs.

**Other Alternatives**

If these approaches are not sufficient or desired, other alternatives could include:

* Using a dedicated regex engine like PCRE (Perl-Compatible Regular Expressions) or Java's `Pattern` class.
* Implementing custom string processing algorithms for better performance.
* Using a different programming language with built-in regex support.

Keep in mind that each alternative may have its own set of trade-offs and considerations.

Related benchmarks:

string.replace vs regexp.matchAll vs regexp.exec (version: 0)

Comparing performance of: string.replace vs regexp.matchAll vs regexp.exec

Created: 2 years ago by: Guest

Jump to the latest result

string.replace

regexp.matchAll

regexp.exec

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):