Benchmark: Regex vs string compare

Script Preparation code:

var string = "hello";
var regex = /^Hello$/i;

Tests:

Regex
regex.test(string);
String
"hello".toLowerCase() == string

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Regex
String

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36 Edg/118.0.2088.69

Browser/OS: Chrome 118 on Windows

View result in a separate tab

Test name	Executions per second
Regex	6870207.5 Ops/sec
String	16981310.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**Benchmark Definition**

The benchmark definition is a JSON object that describes the test to be performed. In this case, there are two benchmarks:

1. **Regex vs string compare**: This benchmark compares the performance of using regular expressions (regex) with comparing strings directly.
2. **String**: This benchmark tests the performance of converting a string to lowercase.

**Options Compared**

In the Regex vs string compare benchmark, we have two options compared:

* **Regex**: The first option uses the `^` and `$` anchors in a regex pattern to match the entire string "hello" (case-insensitive). The `i` flag at the end of the pattern makes it case-insensitive.
* **String**: The second option directly compares the converted lowercase version of the string `"hello"` with the original string.

**Pros and Cons**

Both approaches have their advantages and disadvantages:

* **Regex**:
	+ Pros: Can be more flexible for complex matching tasks, allows for quantifiers (e.g., `.*`), character classes (e.g., `[abc]`).
	+ Cons: Can be slower due to the overhead of parsing the regex pattern.
* **String**:
	+ Pros: Generally faster and simpler, as it only involves a direct comparison.
	+ Cons: Limited to simple string matching tasks.

The choice between these approaches depends on the specific use case. If you need to perform complex text matching or validation, regex might be a better choice. However, if you're simply comparing strings directly, the plain `toLowerCase()` approach is likely faster and more straightforward.

**Library Usage**

There's no library mentioned in this benchmark definition, so we don't have any additional dependencies to consider.

**Special JS Feature/Syntax**

The benchmark uses the following special JavaScript feature:

* **Regex syntax**: The use of `^`, `$`, `.`, `i` flags, and character classes is specific to regex syntax.
* **String comparison**: This is a basic string operation that's widely supported in most JavaScript engines.

**Other Alternatives**

If you wanted to test different approaches or libraries for this benchmark, some alternatives could be:

* Using a different regex flavor (e.g., PCRE) or engine (e.g., URegex)
* Comparing strings using other methods (e.g., using Unicode code points, bit manipulation)
* Testing the performance of compiled regex engines (e.g., esprima, acorn)
* Using a string comparison library like `lodash` or `string-patch`

Keep in mind that the choice of alternative would depend on the specific requirements and goals of your benchmarking effort.

Related benchmarks:

Regex vs string compare (version: 0)

Comparing performance of: Regex vs String

Created: one year ago by: Registered User

Jump to the latest result

Regex

String

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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