Benchmark: Regex vs split/join with simple replace

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, '-');
Split and Join
str.split('_').join('-');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Regex
Split and Join

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

I'll break down the benchmark and explain what's being tested, compared, and the pros/cons of each approach.

**What is being tested?**

The provided JSON represents two individual test cases:

1. **Regex**: The first test case uses the `replace()` method with a regular expression to replace all underscores (`_`) in a string with hyphens (`-`).
2. **Split and Join**: The second test case uses the `split()` method to split the input string into an array of substrings based on the underscore character, followed by the `join()` method to concatenate these substrings back together with hyphens.

**Options compared**

In this benchmark, two approaches are being compared:

1. **Regex**: Using regular expressions to replace substrings in a string.
2. **Split and Join**: Using the `split()` and `join()` methods to process a string.

**Pros/Cons of each approach:**

1. **Regex**
	* Pros:
		+ Can be highly efficient for specific use cases, as it can avoid creating new strings by modifying the original one.
		+ Provides a high degree of flexibility with pattern matching and replacements.
	* Cons:
		+ Can be slower than simple string manipulation methods like `split()` and `join()`, especially for large strings or complex patterns.
		+ Requires more expertise to write effective regular expressions, which can lead to performance issues if not implemented correctly.
2. **Split and Join**
	* Pros:
		+ Generally faster than using regular expressions, as it avoids the overhead of pattern matching and replacement.
		+ Easier to understand and maintain for simple string manipulation tasks.
	* Cons:
		+ Creates new strings during processing, which can be inefficient for large strings or when memory is limited.

**Library/Library purpose**

Neither of these test cases uses a JavaScript library. The `split()` and `join()` methods are part of the JavaScript Standard Library, which provides a set of fundamental functions that all browsers and Node.js environments support.

**Special JS feature/syntax**

There are no special JavaScript features or syntax used in this benchmark. Both test cases only use standard JavaScript language constructs.

**Other alternatives**

If you need to compare other approaches for string manipulation tasks, some alternative methods might include:

1. **Substitution**: Similar to `replace()`, but uses a more explicit syntax and may be slower due to the overhead of creating new strings.
2. **String iteration**: Iterating over each character in the string using a loop or recursion can provide fine-grained control but may be less efficient than using built-in methods like `split()` and `join()`.
3. **Regular expression engines**: While not typically used for simple string manipulation tasks, regular expression engines like RegExp can offer better performance for complex patterns.

In summary, this benchmark compares the efficiency of two common JavaScript string manipulation approaches: using regular expressions (`replace()`) versus simple string splitting and joining methods (`split()` and `join()`).

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.93 Safari/537.36

Browser/OS: Chrome 96 on Windows

View result in a separate tab

Test name	Executions per second
Regex	886865.6 Ops/sec
Split and Join	1041992.4 Ops/sec

Related benchmarks:

Regex vs split/join with simple replace (version: 0)

Comparing performance of: Regex vs Split and Join

Created: 4 years ago by: Guest

Jump to the latest result

Regex

Split and Join

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):