Benchmark: single regex vs double regex vs for loop

Script Preparation code:

var str = 'aasd-asdasd-fegdfg-werwerwer-dsfsdfsdf-sadfsdfsdf-asd-asdasdasdasd-asdasdasd-dssdfhsd-dsfsdfsd-sdfsdfsdf';
var size = str.length;
var regexCombined = /(^.)|-/g;
var regexFirst = /^./
var regexDash = /-/g

Tests:

regex combined
return str.replace(regexCombined, (s) => s === '-' ? ' ' : s.toUpperCase())
double regex
return str.replace(regexDash, ' ').replace(regexFirst, s => s.toUpperCase())
for loop
var result = ''; var i = 0; var char = ''; for (i = 0; i < size; i++) { char = str[i]; if (i === 0) { result += char.toUpperCase(); } else { result += char === '-' ? ' ' : char ; } } return result

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regex combined
double regex
for loop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 144 on Android

View result in a separate tab

Test name	Executions per second
regex combined	627515.4 Ops/sec
double regex	1029419.4 Ops/sec
for loop	1067895.0 Ops/sec

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

LLMs can make mistakes. Check important info.

The provided JSON represents a JavaScript benchmark test case, specifically designed to compare the performance of three different approaches: using a single regular expression (regex) with an arrow function as the replacement callback, using two separate regex patterns, and using a for loop.

**Options being compared:**

1. **Single Regex**: This approach uses a single regex pattern (`regexCombined`) that matches both the hyphens and the other characters in the string. The arrow function is used as the replacement callback to convert only the hyphens to spaces.
2. **Double Regex**: This approach uses two separate regex patterns: `regexDash` to match hyphens only, and `regexFirst` to match the first character only (in this case, it's just the caret `^`). The string is replaced with a space using `regexDash`, and then again with an uppercase version of the first character using `regexFirst`.
3. **For Loop**: This approach uses a for loop to iterate over the characters in the string, checking if each character is a hyphen or not. If it's a hyphen, it's replaced with a space; otherwise, it's converted to uppercase.

**Pros and Cons of each approach:**

1. **Single Regex**:
	* Pros: Less code, potentially faster execution due to fewer function calls.
	* Cons: May have slower performance if the regex engine is not optimized for this specific pattern.
2. **Double Regex**:
	* Pros: More explicit and readable code, can be more efficient if the regex patterns are optimized.
	* Cons: More code, may lead to slower execution due to additional function calls.
3. **For Loop**:
	* Pros: Most straightforward and easy-to-understand approach, can be highly performant due to direct access to individual characters.
	* Cons: May have higher memory overhead due to the need to store the entire string in variables.

Other considerations:

* The use of arrow functions in the single regex approach provides a concise way to define the replacement callback.
* The double regex approach allows for more explicit and readable code, but may not be as efficient as other approaches.
* The for loop approach is the most straightforward and easy-to-understand, but requires more manual management of variables.

**Libraries used:**

None are explicitly mentioned in the provided JSON. However, it's likely that the benchmark test case relies on built-in JavaScript functions and data structures (e.g., strings, regex patterns) rather than external libraries.

**Special JS features or syntax:**

The use of arrow functions (`=>`) is a relatively modern feature introduced in ECMAScript 2015. It provides a concise way to define small, single-expression functions.

Other alternatives:

* **Using `replace()` with a string and a callback function**: Instead of using regex patterns, one could use the `replace()` method with a string and a callback function as the replacement value.
* **Using `map()` or `reduce()`**: Depending on the specific requirements, other functional programming approaches like `map()` or `reduce()` might be suitable for replacing characters in a string.
* **Native support for character classification**: Some browsers may have native support for character classification (e.g., checking if a character is a hyphen), which could potentially improve performance.

Note that these alternatives are not explicitly mentioned in the provided JSON, but they might be worth considering depending on the specific requirements of the benchmark test case.

Related benchmarks:

single regex vs double regex vs for loop (version: 0)

Comparing performance of: regex combined vs double regex vs for loop

Created: 3 years ago by: Guest

Jump to the latest result

regex combined

double regex

for loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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