Benchmark: Reverse array / reverse vs map

Script Preparation code:

test = ["a", "b", "c", "d", "e"];

Tests:

ES Reverse / in place
test.reverse()
ES map
[...test].map(test.pop, test)

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Chrome 12 runs

ES Reverse / in place

11.8M/s

ES map

4.3M/s

Fastest: ES Reverse / in place (2.8x faster)

View exact numbers

✓ ES Reverse / in place: 11,782,304 ops/sec
• ES map: 4,279,121 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
ES Reverse / in place
ES map

Fastest: N/A

Slowest: N/A

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/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Windows

View result in a separate tab

ES Reverse / in place

73.7M/s

ES map

47.6M/s

View exact numbers

Test name	Executions per second
✓ ES Reverse / in place	73,725,328 Ops/sec
ES map	47,644,748 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The provided JSON represents a benchmark with two test cases: Reverse array / reverse vs map. This benchmark tests the performance of reversing an array in place versus using the `map()` method.

**Test Cases**

There are two test cases:

1. **ES Reverse / in place**: This test case uses the `reverse()` method to reverse the array in place.
2. **ES map**: This test case uses the `map()` method with a callback function to create a new array with the reversed elements.

**Options Compared**

The two test cases are compared in terms of their performance on reversing an array.

**Pros and Cons of Different Approaches**

1. **In-Place Reversal (ES Reverse)**:
	* Pros: It modifies the original array, so it only requires a single memory allocation.
	* Cons: It can be slower than creating a new array due to the overhead of modifying the existing array.
2. **Creating a New Array with map (ES Map)**:
	* Pros: It creates a new array, which can be faster than in-place reversal for large arrays.
	* Cons: It requires additional memory allocation and copying of elements.

**Library Used**

The `map()` method is used with a callback function to create a new array. The library used here is the built-in JavaScript `Array.prototype.map()` method.

**Special JS Features or Syntax**

None mentioned in this benchmark.

**Other Alternatives**

There are other alternatives for reversing an array, such as:

1. **Using `slice()`, `concat()`, and `reverse()`**: This approach creates a new array by concatenating the reversed elements.
2. **Using a loop**: A simple loop can be used to reverse an array in place.
3. **Using `reduce()`**: An array can be reversed using the `reduce()` method, which is less common than other methods.

**Benchmark Preparation Code**

The provided JSON includes two scripts:

1. `test = [\"a\", \"b\", \"c\", \"d\", \"e\"];`: Creates an array of strings.
2. No HTML preparation code is provided.

**Latest Benchmark Result**

The latest benchmark result shows the performance of both test cases on a specific browser (Chrome 127) and device platform (Desktop). The results are:

* ES Reverse / in place: 3,859,801 executions per second
* ES Map: 1,483,106.125 executions per second

These results suggest that in-place reversal (ES Reverse) is faster than creating a new array with `map()` (ES Map) on this specific hardware and software configuration.

Reverse array / reverse vs map (version: 0) Benchmark.js

Comparing performance of: `ES Reverse / in place vs ES map`

Created: 5 years ago by: Guest

Go to the latest result

ES Reverse / in place

ES map

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Chrome 12 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Reverse array / reverse vs map (version: 0) Benchmark.js

Comparing performance of: ES Reverse / in place vs ES map

Created: 5 years ago by: Guest

Go to the latest result

ES Reverse / in place

ES map

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Chrome 12 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `ES Reverse / in place vs ES map`