Benchmark: Joined RegExp vs looping

Tests:

Joined regexp
const toReplace = ['a', 'b', 'c']; const regexp = new RegExp(toReplace.join("|"), "g"); "abcdefgabcdefgabcdefg".replace(regexp, '*');
loop
const toReplace = ['a', 'b', 'c']; const sample = "abcdefgabcdefgabcdefg" toReplace.forEach((letter) => { sample.replace(new RegExp(letter, "g"), "*") })
single replace
const regexp = new RegExp("a", "g"); "aaadefgaaadefgaaadefg".replace(regexp, '*');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Joined regexp
loop
single replace

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36

Browser/OS: Chrome 100 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Joined regexp	1127278.6 Ops/sec
loop	673591.7 Ops/sec
single replace	1593039.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and its test cases.

**What is being tested?**

The benchmark measures the performance of different approaches for replacing characters in a string using regular expressions (REGEX). Specifically, it compares three methods:

1. Joined REGEX: Using a single REGEX pattern with joined character classes (`'a|b|c'`) to replace all occurrences of 'a', 'b', or 'c'.
2. Looping: Iterating over an array of characters and using `replace()` method on each iteration.
3. Single Replace: Using a single REGEX pattern with a specific character class (`'a'`) to replace only 'a' occurrences.

**Options compared**

The benchmark compares the performance of these three approaches:

* Joined REGEX: This approach is more efficient because it uses a single REGEX pattern and reduces the number of regex engine calls.
* Looping: This approach is less efficient because it uses multiple `replace()` method calls, which can be slower than using a single regex engine call.
* Single Replace: This approach is similar to Joined REGEX but with only one character class.

**Pros and Cons**

* Joined REGEX:
	+ Pros: More efficient, reduces the number of regex engine calls.
	+ Cons: Can be less readable and maintainable if the character classes are complex or large.
* Looping:
	+ Pros: Can be more readable and maintainable for small arrays of characters.
	+ Cons: Less efficient due to multiple `replace()` method calls.
* Single Replace:
	+ Pros: Similar to Joined REGEX but with only one character class, can be easier to read and maintain.
	+ Cons: May not be as efficient as Joined REGEX.

**Libraries used**

None of the test cases explicitly use a library. However, the `RegExp` constructor is used in each test case, which is a built-in JavaScript function for creating regular expressions.

**Special JS feature/syntax**

The test cases do not use any special JavaScript features or syntax beyond what's typically available in most JavaScript engines. They only rely on basic language constructs like functions, loops, and object methods.

**Other alternatives**

If you're looking to optimize string replacement performance, you may also consider using:

* `String.prototype.replaceAll()` method: This is a newer method in ECMAScript 2019+ that provides a more efficient way to replace all occurrences of a substring.
* Using `String.prototype.replace()` with a callback function: Instead of using a regular expression pattern, you can use an anonymous function as the second argument to `replace()`, which allows for more flexible replacement logic.

Keep in mind that these alternatives may have different performance characteristics and trade-offs compared to the approaches tested in this benchmark.

Related benchmarks:

Joined RegExp vs looping (version: 0)

Comparing performance of: Joined regexp vs loop vs single replace

Created: 2 years ago by: Guest

Jump to the latest result

Joined regexp

loop

single replace

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):