Benchmark: Cache js regex - MeasureThat.net

Script Preparation code:

var regex = /^\d+$/;

var regularTest = value => {
    const pass = /^\d+$/.test(value);
    return !pass;
};

var cachedTest = value => {
  const pass = regex.test(value);
  return !pass;
};

Tests:

Not Cached
regularTest(555);
Cached
cachedTest(555);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Not Cached
Cached

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_5 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.5 Mobile/15E148 Safari/604.1

Browser/OS: Mobile Safari 18 on iOS 18.5

View result in a separate tab

Test name	Executions per second
Not Cached	57120920.0 Ops/sec
Cached	59338216.0 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 benchmark and explain what's being tested.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark that tests the performance of two functions, `regularTest` and `cachedTest`, which are used to check if a given string matches a specific regular expression. The regular expression in question is `^\\d+$`, which matches one or more digits from start to end.

**Regular Test (`regularTest`)**

The `regularTest` function takes a string as input, tests it against the regular expression using the `test()` method, and returns a boolean indicating whether the string does not match the pattern. This approach relies on the interpreter's ability to compile and execute the regular expression.

Pros:

* Simple implementation
* Easy to understand

Cons:

* May incur additional overhead due to the interpretation of the regular expression
* Can be slower for large inputs or complex patterns

**Cached Test (`cachedTest`)**

The `cachedTest` function uses a cached version of the regular expression, which is created by compiling it once and storing it in a variable. The function then uses this pre-compiled expression to test the input string.

Pros:

* Can be faster for repeated tests, as the compilation step is only performed once
* Reduces interpreter overhead

Cons:

* Requires more memory allocation due to the cached regex object
* May not be suitable for small inputs or simple patterns

**Library Used**

The `test()` method and regular expression syntax are part of the JavaScript standard library. The `regex` variable in the `cachedTest` function is a local variable created using the `new RegExp()` constructor, which allows us to compile and store the regular expression.

**Other Considerations**

* **Performance Impact**: For small inputs or simple patterns, the difference between the two approaches may be negligible. However, for larger inputs or more complex patterns, the cached version of `cachedTest` is likely to perform better.
* **Memory Usage**: The cached version of `cachedTest` uses additional memory to store the pre-compiled regex object. This may not be a concern for small inputs but could become significant for very large datasets.
* **Code Readability and Maintainability**: While both implementations are straightforward, the cached version of `cachedTest` might be considered less readable due to its use of internal state.

**Alternatives**

Some alternative approaches that could be explored include:

1. Using a dedicated regex engine or library like [regexninja](https://github.com/masfenix/regexninja) for more complex patterns.
2. Implementing the regular expression using a just-in-time (JIT) compiler or a native code generator to achieve better performance.
3. Using a caching mechanism that does not rely on internal state, such as a WeakMap-based cache.

Please note that these alternatives might come with additional complexity and dependencies, which may not be suitable for all use cases.

Related benchmarks:

Cache js regex (version: 0)

Comparing performance of: Not Cached vs Cached

Created: 6 years ago by: Guest

Jump to the latest result

Not Cached

Cached

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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