Benchmark: Regex vs Split and pop

Script Preparation code:

var str = 'Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxyAbcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy Abcd efghij klmnopqrstuv wxy';

Tests:

Regex
str.replace(/./g, "$&Z");
Split and pop
str.split('').pop('Z') + 'Z';

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Regex
Split and pop

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0

Browser/OS: Firefox 128 on Ubuntu

View result in a separate tab

Test name	Executions per second
Regex	63896.8 Ops/sec
Split and pop	1159890.4 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 its pros/cons.

**Benchmark Overview**

The benchmark is designed to compare two approaches for manipulating strings in JavaScript:

1. **Regex**: Using regular expressions (`str.replace(/./g, \"$&Z\");`) to modify the string.
2. **Split and pop**: Splitting the string into an array using `str.split('')` and then popping off the last element with `'Z'`, followed by concatenating it with `'Z'`.

**Test Case Comparison**

The two test cases compare the performance of these two approaches on a large input string (`str`). The input string is created by repeating a substring (`Abcd efghij klmnopqrstuv wxy`) multiple times.

**Approach 1: Regex**

Pros:

* Can be used to perform complex string manipulations, such as validation and extraction.
* Often faster than split and pop for small strings.

Cons:

* Can be slower than split and pop for large strings due to the overhead of regular expression compilation and execution.
* May have performance issues with very long or complex regex patterns.

**Approach 2: Split and pop**

Pros:

* Typically faster than regex for large strings, as it avoids the overhead of regular expression compilation and execution.
* Can be more memory-efficient, as it doesn't require storing a compiled regex pattern.

Cons:

* May be slower than regex for small strings due to the additional overhead of splitting and popping the array.
* Less flexible than regex, as it can only be used for simple string manipulation.

**Library Used**

None is explicitly mentioned in the benchmark definition, but `str.split('')` uses a built-in JavaScript method. However, some versions of JavaScript (e.g., older browsers) may not support this method or may have performance issues with large strings.

**Special JS Feature/Syntax**

The benchmark doesn't use any special JavaScript features or syntax that's not widely supported across different browsers and environments.

**Other Alternatives**

For string manipulation benchmarks like this one, other alternatives to test include:

* Using a different string manipulation approach, such as using `String.prototype.replace()` with a custom function.
* Adding additional complexity to the input string, such as introducing Unicode characters or non-ASCII strings.
* Comparing performance across different JavaScript engines (e.g., V8, SpiderMonkey) or browser versions.

Overall, this benchmark provides a useful comparison of two common string manipulation approaches in JavaScript, allowing developers to evaluate their choice for specific use cases.

Related benchmarks:

Regex vs Split and pop (version: 0)

Comparing performance of: Regex vs Split and pop

Created: 3 years ago by: Guest

Jump to the latest result

Regex

Split and pop

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):