Benchmark: Reverse string with more tests

Script Preparation code:

var string = document.documentElement.outerHTML.repeat(100);

Tests:

Array.from, reverse, join
Array.from(string).reverse().join("");
Iterate, concat
var newString = ""; for (let i = string.length - 1; i--;) { newString += string[i]; }
Iterate, push, join
var newChars = []; for (let i = string.length - 1; i--;) { newChars.push(string[i]); } newChars.join("")
iterate concat to first (charAt)
let i = string.length - 1; let result = string.charAt(i); for (;i--;) { result += string.charAt(i); }
iterate concat to first
let i = string.length - 1; let result = string[i]; for (;i--;) { result += string[i]; }
split, iterate, concat to first
const parts = string.split(""); let i = parts.length - 1; let result = parts[i]; for (;i--;) { result += parts[i]; }
split, reverse, join
string.split("").reverse().join("");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.from, reverse, join
Iterate, concat
Iterate, push, join
iterate concat to first (charAt)
iterate concat to first
split, iterate, concat to first
split, reverse, join

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array.from, reverse, join	255.3 Ops/sec
Iterate, concat	107.2 Ops/sec
Iterate, push, join	83.2 Ops/sec
iterate concat to first (charAt)	105.6 Ops/sec
iterate concat to first	106.6 Ops/sec
split, iterate, concat to first	422.5 Ops/sec
split, reverse, join	319.7 Ops/sec

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The benchmark tests the performance of different methods to reverse a string in JavaScript. The test cases cover various approaches using built-in array and string methods, as well as custom implementations.

**Test Cases**

1. **Array.from, reverse, join**: This method uses `Array.from()` to convert the string into an array, `reverse()` to reverse the array, and finally `join()` to concatenate the characters back into a string.
2. **Iterate, concat**: This method uses a simple loop to iterate over the string in reverse order and concatenates each character to a new string using `+=`.
3. **Iterate, push, join**: Similar to the previous method, but instead of concatenating each character directly, it pushes each character onto an array and then joins the array back into a string.
4. **iterate concat to first (charAt)**: This method uses `charAt()` to access each character at the current index, and concatenates the characters in reverse order using `+=`.
5. **iterate concat to first**: Similar to the previous method, but without using `charAt()`.
6. **split, iterate, concat to first**: This method splits the string into an array of individual characters using `split()`, iterates over the array in reverse order, and concatenates each character back into a new string.
7. **split, reverse, join**: This method splits the string into an array of individual characters using `split()`, reverses the array using `reverse()`, and finally joins the array back into a string.

**Library Usage**

None of the test cases use any external libraries.

**Special JS Features or Syntax**

1. **Array.from()**: This method creates a new, shallow copy of an array instance from an existing iterable (such as a string). It's not specific to this benchmark.
2. **charAt()**: This method returns the character at the specified index in a string. It's used in test cases 4 and 5.
3. **split()**: This method splits a string into an array of substrings, using a specified separator (default is whitespace). It's used in test cases 6 and 7.

**Other Alternatives**

Some other ways to reverse a string in JavaScript include:

* Using regular expressions (`/[^]*/g`)
* Recursively reversing the string
* Using a library like Lodash or Underscore.js (not applicable here, as no external libraries are used)

The test results show that the fastest method is **split, reverse, join**, which achieves an execution speed of approximately 319.7 executions per second on a desktop device running Chrome 122.

Keep in mind that these performance differences might vary depending on your specific use case, browser version, and system configuration.

Related benchmarks:

Reverse string with more tests (version: 1)

Comparing performance of: Array.from, reverse, join vs Iterate, concat vs Iterate, push, join vs iterate concat to first (charAt) vs iterate concat to first vs split, iterate, concat to first vs split, reverse, join

Created: 4 years ago by: Registered User

Jump to the latest result

Array.from, reverse, join

Iterate, concat

Iterate, push, join

iterate concat to first (charAt)

iterate concat to first

split, iterate, concat to first

split, reverse, join

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):