Benchmark: Re-usable regex - MeasureThat.net

Script Preparation code:

const str = 'catch me if you can';
const regex = /me/;

function runInside() {
  return /me/.test(str);
}

function runOutside() {
  return regex.test(str);
}

Tests:

Inside
runInside();
Outside
runOutside();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Inside
Outside

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

I'd be happy to help explain the benchmark.

**Benchmark Definition:**

The provided JSON represents a JavaScript microbenchmark that tests two approaches for reusing regular expressions (regex) in a loop.

Here's what is being tested:

* `runInside()`: This function calls the `test()` method on the regex object directly, passing the string as an argument.
* `runOutside()`: This function uses the `test()` method on the regex object with no arguments, and then stores the result in a variable before using it.

**Comparison of Options:**

There are two options being compared:

1. **`runInside()`**: This approach calls `test()` directly on the regex object, passing the string as an argument. The `test()` method returns a boolean value indicating whether the string matches the regex.
2. **`runOutside()`**: This approach uses the `test()` method with no arguments and stores the result in a variable before using it.

**Pros and Cons of Each Approach:**

* `runInside()`: Pros:
	+ Easier to read and understand, as it's more straightforward to call `test()` directly.
	+ May be faster, since there's less overhead involved.
Cons:
	+ May have slower performance due to the need to parse the regex every time.
* `runOutside()`: Pros:
	+ May have faster performance, since the regex is parsed only once and stored in a variable.
Cons:
	+ Less readable and maintainable, as it involves an extra step of storing and retrieving the result.

**Library Used:**

The benchmark uses the built-in JavaScript `RegExp` object, which provides methods for testing whether a string matches a regular expression. The `test()` method is used to perform this test.

**Special JS Feature/Syntax:**

This benchmark does not explicitly use any special JavaScript features or syntax, aside from using an array of objects to represent the benchmark definition and individual test cases.

**Other Considerations:**

When writing benchmarks like this one, it's essential to consider factors such as:

* **Overhead**: The amount of overhead involved in executing each benchmark case can affect performance. In this case, the `test()` method has some overhead due to parsing the regex.
* **Cacheability**: How well a benchmark is cacheable can impact performance. In this case, the result of `runOutside()` may be cached by modern browsers, making it faster than `runInside()`.
* **Interpretation**: Benchmarks should always consider interpretation and potential issues with running code in different environments.

**Alternatives:**

Other alternatives for writing benchmarks include:

* Using a benchmarking library like Benchmark.js or micro-benchmark.
* Writing benchmarks using a testing framework like Jest or Mocha.
* Utilizing CPU-specific libraries like perf or jsperf (older) to measure execution time.

Related benchmarks:

Re-usable regex (version: 0)

Comparing performance of: Inside vs Outside

Created: 4 years ago by: Guest

Jump to the latest result

Inside

Outside

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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