Benchmark: Format number | Regex vs Code V1.1

Script Preparation code:

var char = ' '
var count = 3

function formatNumber(num) {
    const arr = num.toString().split('');
    let it = 1;

    for (let i = arr.length - 1; i >= 1; i--) {
        if (it % count === 0) {
            arr.splice(i, 0, char);
        }
        it++;
    }
    return arr.join('');
}

function formatNumber1bis(num) {
    const arr = `${num}`.split('');
    let it = 1;

    for (let i = arr.length - 1; i >= 1; i--) {
        if (it % count === 0) {
            arr.splice(i, 0, char);
        }
        it++;
    }
    return arr.join('');
}

function formatNumber2(num) {
    return num.toString().replace(/\B(?=(\d{3})+(?!\d))/g, char);
}

function formatNumber2bis(num) {
    return `${num}`.replace(/\B(?=(\d{3})+(?!\d))/g, char);
}

Tests:

regex test (toString)
const numbers = [1, 100, 1000, 10000, 100000, 1000000, 10000000, 1000000000] for (let i = 0; i < numbers.length; i++) { formatNumber2(numbers[i]) }
code test (toString)
const numbers = [1, 100, 1000, 10000, 100000, 1000000, 10000000, 1000000000] for (let i = 0; i < numbers.length; i++) { formatNumber(numbers[i]) }
regex test ````
const numbers = [1, 100, 1000, 10000, 100000, 1000000, 10000000, 1000000000] for (let i = 0; i < numbers.length; i++) { formatNumber2bis(numbers[i]) }
code test ````
const numbers = [1, 100, 1000, 10000, 100000, 1000000, 10000000, 1000000000] for (let i = 0; i < numbers.length; i++) { formatNumber1bis(numbers[i]) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regex test (toString)
code test (toString)
regex test ````
code test ````

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**Benchmark Definition JSON**

The provided JSON represents a benchmark definition for a JavaScript function called `formatNumber`. The benchmark compares three different approaches to format numbers:

1. **Regex approach**: Uses regular expressions (regex) to manipulate the number string.
2. **Code V1.1 approach**: Implements a custom implementation using traditional JavaScript coding style.

**Options Compared**

The benchmark compares the performance of two regex-based approaches and two code-based approaches. The options are:

* `formatNumber2` (Regex approach): uses a regex pattern to replace whitespace with the specified character.
* `formatNumber2bis` (Regex approach): uses a similar regex pattern, but applied to a string template literal (`${num}`) instead of a plain string.
* `formatNumber1bis` (Code V1.1 approach): implements a custom implementation using traditional JavaScript coding style.

**Pros and Cons**

Here are some pros and cons for each approach:

* **Regex approach**:
	+ Pros: concise, flexible, and easy to read.
	+ Cons: can be slow due to regex engine overhead and potential backtracking issues.
* **Code V1.1 approach**:
	+ Pros: simple, readable, and potentially faster since it avoids regex engine overhead.
	+ Cons: may not be as concise or flexible as the regex approach.

**Library Usage**

The `String.prototype.replace()` method is used in both regex-based approaches (`formatNumber2` and `formatNumber2bis`). This method replaces occurrences of a pattern with a replacement string. In this case, the pattern is `\\B(?=(\\d{3})+(?!\\d))`, which matches whitespace characters only between groups of three digits (with an optional digit before or after the group).

**Special JavaScript Feature**

The benchmark uses template literals (`${num}`) in some test cases. Template literals are a feature introduced in ECMAScript 2015 that allows embedding expressions inside string literals.

**Other Alternatives**

If you were to implement this benchmark, you could also consider other approaches, such as:

* Using a faster JavaScript engine or compiler
* Optimizing the regex pattern for better performance
* Implementing the `formatNumber` function using a different language (e.g., C++ or Rust)
* Using a benchmarking library like Benchmark.js

Keep in mind that the specific implementation and optimizations will depend on your goals, target audience, and performance requirements.

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/119.0.0.0 Safari/537.36

Browser/OS: Chrome 119 on Windows

View result in a separate tab

Test name	Executions per second
regex test (toString)	828992.1 Ops/sec
code test (toString)	361758.6 Ops/sec
regex test ````	843923.6 Ops/sec
code test ````	366206.4 Ops/sec

Related benchmarks:

Format number | Regex vs Code V1.1 (version: 1)

Regex VS Code for number format

Comparing performance of: regex test (toString) vs code test (toString) vs regex test ```` vs code test ````

Created: 2 years ago by: Registered User

Jump to the latest result

regex test (toString)

code test (toString)

regex test ````

code test ````

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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