Benchmark: Case insensitive RegEx.test vs. String.includes when string doesn’t match

Script Preparation code:

var string = "Hello world!";
var regex = /Hello1/i;

Tests:

RegEx.test
regex.test(string);
String.includes
string.toLowerCase().includes("Hello1");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
RegEx.test
String.includes

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36

Browser/OS: Chrome 145 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
RegEx.test	31884546.0 Ops/sec
String.includes	42054628.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares two approaches for case-insensitive regular expression matching: `regex.test()` and `string.toLowerCase().includes()`. The goal is to determine which approach is faster, especially when a string does not match the regex pattern.

**Test Cases**

There are two test cases:

1. **RegEx.test**: This test case uses a regular expression (`/Hello1/i`) to search for a substring (`"Hello1"`) in a given string (`"Hello world!"`). The `/i` flag makes the matching case-insensitive.
2. **String.includes**: This test case converts the input string to lowercase using `string.toLowerCase()` and then checks if the lowercase version of the regex pattern (`"Hello1"`) is included in the original string.

**Options Compared**

The two approaches are compared in terms of performance (executions per second).

* **RegEx.test()**: This approach uses a built-in JavaScript method for regular expression testing, which likely employs an optimized algorithm and engine.
* **string.toLowerCase().includes()**: This approach uses the `includes()` method on a string that has been converted to lowercase. The `includes()` method is a more general-purpose string searching function.

**Pros and Cons**

Here's a brief analysis of each approach:

* **RegEx.test()**:
	+ Pros: Typically faster and more efficient for regular expression matching.
	+ Cons: May require additional memory allocation and processing power if the regex pattern is complex.
* **string.toLowerCase().includes()**:
	+ Pros: Often simpler to implement and may be more suitable for simple string searching tasks.
	+ Cons: Can be slower due to the need to convert the input string to lowercase, which can lead to increased memory usage.

**Library**

In this benchmark, `regex` is a built-in JavaScript object that provides methods for working with regular expressions. The `String.includes()` method is also a built-in JavaScript method for checking if a substring exists within another string.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntax used in this benchmark. However, it's worth noting that the `/i` flag in the RegEx pattern enables case-insensitive matching.

**Other Alternatives**

Other approaches to regular expression matching or string searching might include:

* Using a dedicated library like `regex-escape` or `regex-utils`
* Implementing a custom regex engine
* Using a different string searching algorithm, such as a Boyer-Moore search

Keep in mind that these alternatives may not be relevant to the specific use case of this benchmark.

Related benchmarks:

Case insensitive RegEx.test vs. String.includes when string doesn’t match (version: 0)

Comparing performance of: RegEx.test vs String.includes

Created: 3 years ago by: Guest

Jump to the latest result

RegEx.test

String.includes

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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