Benchmark: String replace using regex vs string

Script Preparation code:

var string = '-firstDeadlineReminderData__PS__assignment__PS__perEntityType__PS__Applicant__PS__hasDeadline'
var regExp = new RegExp('__PS__', 'g');

Tests:

replace by regex
var res = string.replace(regExp, '.')
replace via string
var res = string.split('__PS__').join('.');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
replace by regex
replace via string

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 14 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
replace by regex	5054176.0 Ops/sec
replace via string	3974552.5 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.

**Benchmark Definition**

The benchmark definition consists of two separate test cases, each with its own script preparation code and description. The test cases are:

1. "replace by regex"
2. "replace via string"

These test cases aim to measure the performance difference between using a regular expression (regex) for string replacement and using the `split()` method for string manipulation.

**Script Preparation Code**

The script preparation code defines two variables:

* `string`: a string containing a specific value with multiple occurrences of `__PS__`.
* `regExp`: a regex object that matches the pattern `__PS__`.

This setup is used to perform both test cases: one using the regular expression and the other using the `split()` method.

**Test Cases**

The two test cases are:

1. "replace by regex": This test case uses the regular expression to replace all occurrences of `__PS__` with a period (`.`) in the string.
2. "replace via string": This test case uses the `split()` method to split the string into an array, removes the unwanted substring `__PS__`, and then joins the remaining parts back together using a period (`.`).

**Comparison of Approaches**

The two approaches have different characteristics:

* **Regular Expression**: This approach uses a regex object to match a pattern in the string. Regex is powerful for searching patterns but can be slow for large strings due to its overhead.
* **String Splitting**: This approach uses the `split()` method, which is a built-in JavaScript function that splits a string into an array of substrings based on a specified separator.

Pros and Cons:

* **Regex**:
	+ Pros: Can handle complex patterns, flexible, and powerful for searching specific values.
	+ Cons: Can be slow for large strings due to its overhead, and may not work as expected if the pattern is not correctly defined.
* **String Splitting**:
	+ Pros: Fast for large strings, easy to understand, and widely supported by JavaScript engines.
	+ Cons: Limited to splitting on a specific separator, which might require more code to achieve similar results.

**Library Usage**

Neither of these test cases uses an external library. They rely solely on built-in JavaScript functions and the `RegExp` object for regex matching.

**Special JavaScript Feature/Syntax**

There is no special JavaScript feature or syntax used in this benchmark. The approaches are straightforward and use well-known methods.

**Other Alternatives**

If you wanted to improve performance, you could consider:

* Using a more efficient string manipulation library like ICU (International Components for Unicode).
* Optimizing the regex pattern for better matching.
* Using a Just-In-Time (JIT) compiler like SpiderMonkey in Firefox or V8 in Chrome to compile and optimize the JavaScript code.

Keep in mind that these alternatives are not directly applicable to this specific benchmark, but they can be useful for optimizing similar performance-critical code paths.

Related benchmarks:

String replace using regex vs string (version: 0)

Comparing performance of: replace by regex vs replace via string

Created: 2 years ago by: Guest

Jump to the latest result

replace by regex

replace via string

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):