Benchmark: Unnecessary non-capturing groups

Script Preparation code:

var loremString = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
var unneededNonCaptureRE = /(?:z)+/
var noNonCaptureRE = /z+/
var anotherUnneededNonCapture = /lab(?:o)rum/
var anotherNoNonCapture = /laborum/

Tests:

unneededNonCaptureRE
unneededNonCaptureRE.exec(loremString)
noNonCaptureRE
noNonCaptureRE.exec(loremString)
anotherUnneededNonCapture
anotherUnneededNonCapture.exec(loremString)
anotherNoNonCapture
anotherNoNonCapture.exec(loremString)
indexOf
loremString.indexOf('laborum')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
unneededNonCaptureRE
noNonCaptureRE
anotherUnneededNonCapture
anotherNoNonCapture
indexOf

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.115 Safari/537.36

Browser/OS: Chrome 59 on Linux

View result in a separate tab

Test name	Executions per second
unneededNonCaptureRE	2384496.2 Ops/sec
noNonCaptureRE	2380136.8 Ops/sec
anotherUnneededNonCapture	3488588.2 Ops/sec
anotherNoNonCapture	2545632.2 Ops/sec
indexOf	12354694.0 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 on MeasureThat.net.

The benchmark being tested is the performance difference between using parentheses in regular expressions and not using them, as discussed in this Stack Overflow question: https://stackoverflow.com/questions/45291700/javascript-regex-non-capture-faster-than-no-parenthesis-at-all

In essence, the test cases are comparing the execution speed of different regex patterns that match a specific string. The variations are:

1. `unneededNonCaptureRE`: `/(?:z)+/` (non-capturing group)
2. `noNonCaptureRE`: `/z+/\` (no non-capturing group)
3. `anotherUnNeededNonCapture`: `/lab(?:o)rum/` (another variation with a non-capturing group)
4. `anotherNoNonCapture`: `/laborum/` (no non-capturing group)
5. `indexOf`: `loremString.indexOf('laborum')`

Let's break down the pros and cons of each approach:

**Non-capturing groups (`?:`)**

Pros:

* Faster execution speed, as it avoids creating an additional capturing group.
* Can be useful when you need to match a specific pattern without capturing the matched text.

Cons:

* May not work correctly in some situations where you rely on capturing groups (e.g., `RegExp.prototype.exec()`).

**No non-capturing group (`z+`)**

Pros:

* Works similarly to non-capturing groups but still allows for faster execution speed.
* Can be used when you need to match a specific pattern and also want to capture the matched text.

Cons:

* May not be as efficient as non-capturing groups in some cases.

**Simple string matching (`indexOf`)**

Pros:

* Fastest execution speed, as it uses a simple string search algorithm.
* Easy to understand and implement.

Cons:

* Limited functionality compared to regex patterns.

Now, let's discuss the libraries used in this benchmark:

None. This is a basic JavaScript microbenchmark.

No special JS features or syntax are used in this benchmark. The tests only rely on standard JavaScript features and the `RegExp` class.

As for alternatives, here are some other ways to measure performance differences in JavaScript regex patterns:

1. **Benchmarking libraries**: Libraries like Benchmark.js or js-benchmark provide more advanced benchmarking capabilities and can help you create more robust test cases.
2. **Regex testing frameworks**: Frameworks like Regex Tester or RegexBuddy allow you to visualize and analyze regex patterns, which can be helpful when optimizing performance.

In summary, this benchmark on MeasureThat.net is a simple yet informative test that highlights the performance differences between using parentheses in regular expressions and not using them. By understanding the pros and cons of each approach, developers can make informed decisions about how to optimize their regex patterns for better performance.

Related benchmarks:

Unnecessary non-capturing groups (version: 0)

https://stackoverflow.com/questions/45291700/javascript-regex-non-capture-faster-than-no-parenthesis-at-all

Comparing performance of: unneededNonCaptureRE vs noNonCaptureRE vs anotherUnneededNonCapture vs anotherNoNonCapture vs indexOf

Created: 7 years ago by: Guest

Jump to the latest result

unneededNonCaptureRE

noNonCaptureRE

anotherUnneededNonCapture

anotherNoNonCapture

indexOf

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):