Benchmark: RegExp.exec vs String.match +

Script Preparation code:

var fnSelectorStr = "functionsomethingreturnsomething.foo['bar']['barz'].bar_again['foo_again']['barz-again']['idk']";

var RE_MATCH = /(?:(?<=\[)(['"]).*?\1)|(?:(?<=\.)[^.[]+)/g;
var RE_EXEC = /(?:(?<=\[)(['"])(.*?)\1)|(?:(?<=\.)[^.[]+)/g;

Tests:

exec
var matches = RE_EXEC.exec(fnSelectorStr); var members = []; do { var propFound = matches[2] === undefined ? matches[0] : matches[2]; members.push(propFound); } while ((matches = RE_EXEC.exec(fnSelectorStr)) !== null); console.log(members);
match + map + N x match
var matches = fnSelectorStr.match(RE_MATCH); if (matches) { var RE_HAS_QUOTES = /^(['"]).*\1$/; return matches.map(function(match){ return match.match(RE_HAS_QUOTES) ? match.slice(1, -1) : match; }); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
exec
match + map + N x match

Fastest: N/A

Slowest: N/A

Latest run results:

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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 its components.

**Benchmark Overview**

The benchmark measures the performance of two different approaches to extract data from a string:

1. `RegExp.exec`
2. `String.match +` (which involves additional processing, such as mapping and trimming)

**Comparison Options**

The benchmark compares the performance of these two approaches on the same input data. The main difference between them lies in how they process the extracted matches.

* `RegExp.exec`: This method returns a single match array with the matched text and its starting index.
* `String.match`: This method returns an array of all matches found in the string. In this case, it's used as a fallback if `RegExp.exec` doesn't find any matches.

**Pros and Cons**

Here are some pros and cons of each approach:

* `RegExp.exec`:
	+ Pros:
		- More straightforward to use for simple regex patterns.
		- Can be more efficient if only one match is expected.
	+ Cons:
		- May require more code to handle multiple matches or extract specific parts of the match.
		- Can be slower if the regex pattern is complex.
* `String.match +`:
	+ Pros:
		- Handles multiple matches and can be used to process each individual match.
		- Provides a simple way to trim or transform the extracted data.
	+ Cons:
		- Requires an additional step to handle the matched array, which might add overhead.

**Library Usage**

In this benchmark, the `RegExp` object is used for both approaches. The `RegExp` constructor takes two arguments: a pattern and a flags value. In this case, no flags are specified, so it defaults to the basic regex syntax.

**Special JS Features or Syntax**

This benchmark does not use any special JavaScript features or syntax beyond regular expressions. It relies on standard ECMAScript language features.

**Other Considerations**

When choosing between these approaches, consider the following factors:

* Complexity of your regex patterns: If you're working with complex patterns, `RegExp.exec` might be a better choice to avoid unnecessary processing.
* Frequency of multiple matches: If you expect to find multiple matches or need to process each individual match, `String.match +` might provide more flexibility and efficiency.

**Alternative Approaches**

If you need to extract data from strings in JavaScript, other approaches worth considering include:

* Using the `String.prototype.split()` method with a regex pattern to split the string into an array of substrings.
* Utilizing the `Array.prototype.map()` method to transform individual elements of an array.
* Leveraging modern JavaScript features like template literals or regex literal syntax for more concise and expressive code.

Keep in mind that the choice of approach ultimately depends on your specific use case, performance requirements, and personal coding preferences.

Related benchmarks:

RegExp.exec vs String.match + (version: 0)

not realistic benchmark to adress https://github.com/nartc/mapper/pull/293

Comparing performance of: exec vs match + map + N x match

Created: 5 years ago by: Guest

Jump to the latest result

exec

match + map + N x match

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):