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Array reverse
(version: 0)
Comparing performance of:
Reverse (unmodified) vs Reverse (modified) vs Map reverse
Created:
2 years ago
by:
Guest
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Script Preparation code:
var test = ["a", "b", "c", "d", "e"];
Tests:
Reverse (unmodified)
test.slice().reverse()
Reverse (modified)
test.reverse()
Map reverse
var max = test.length - 1; test.map((a,index,list) => list[max - index])
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
Reverse (unmodified)
Reverse (modified)
Map reverse
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'd be happy to explain the provided benchmark and its different approaches. **What is being tested?** The provided benchmark tests the execution speed of three different methods for reversing an array in JavaScript: 1. **`test.slice().reverse()`**: This method creates a shallow copy of the original array using `slice()`, and then reverses the copied array using `reverse()`. 2. **`test.reverse()`**: This method modifies the original array by reversing its elements in place. 3. **`var max = test.length - 1; test.map((a, index, list) => list[max - index])`**: This method uses a combination of variables and the `map()` function to create a new array with the reversed order of elements. **Options compared** The three approaches are being compared in terms of their execution speed. The benchmark measures the number of executions per second for each approach on a given machine. **Pros and cons of each approach:** 1. **`test.slice().reverse()`**: This approach is safe to use, as it creates a shallow copy of the original array without modifying its contents. However, it can be slower than other approaches since it involves creating an additional array. * Pros: Safe, easy to understand and implement. * Cons: Can be slower due to extra memory allocation. 2. **`test.reverse()`**: This approach modifies the original array in place, which can lead to unexpected side effects if used in a larger program. However, it is generally faster than other approaches since it only involves modifying the existing array. * Pros: Fastest execution time. * Cons: May be considered unsafe or unpredictable due to potential side effects. 3. **`var max = test.length - 1; test.map((a, index, list) => list[max - index])`**: This approach uses a combination of variables and the `map()` function to create a new array with the reversed order of elements. * Pros: Can be more efficient than other approaches since it only involves modifying an existing array. * Cons: May require additional variables and can be harder to understand for some developers. **Library used** None of the provided benchmark definitions use any external libraries beyond JavaScript's built-in `slice()` and `reverse()` methods, as well as the `map()` function. **Special JS feature or syntax** The benchmark does not use any special JavaScript features or syntax, such as async/await, promises, or modern ECMAScript syntax (e.g., arrow functions, template literals). **Other alternatives** If you wanted to test other approaches for reversing an array in JavaScript, some additional methods might include: * Using a library like Lodash's `reverse()` method. * Implementing a custom recursive function to reverse the array. * Using a streaming algorithm to reverse the array without creating an intermediate array. However, the three provided approaches (`slice().reverse()`, `reverse()`, and `map()` with indices) are among the most common and efficient ways to reverse an array in JavaScript.
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