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slice VS splice VS shift for fixed size array
(version: 0)
Comparing performance of:
slice vs splice vs shift-while
Created:
5 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var count = 120000; var list = new Array(count).fill(100);
Tests:
slice
list.push(count + 1) if (list.length > count) { list=list.slice(0, count) }
splice
list.push(count + 1) if (list.length > count) { list.splice(0, list.length - count); }
shift-while
list.push(count + 1) while (list.length > count) { list.shift(); }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
slice
splice
shift-while
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks. **Benchmark Definition** The provided JSON represents a benchmark definition for three test cases: `slice`, `splice`, and `shift-while`. The benchmark aims to measure the performance of different methods for reducing the size of an array by removing elements while preserving the original sequence. **Test Case 1: slice** In this test case, the benchmark uses the `Array.prototype.slice()` method to create a new array containing only the first `count` elements of the original array. The `if (list.length > count)` condition is used to check if the array has exceeded its initial size and trigger the slicing operation. Pros: * `slice()` is generally considered one of the fastest methods for creating a subset of an array. * It is widely supported by most browsers and JavaScript engines. Cons: * Creating a new array using `slice()` can be memory-intensive, especially for large arrays. * The overhead of creating a new array might outweigh any potential speed gains for small arrays. **Test Case 2: splice** In this test case, the benchmark uses the `Array.prototype.splice()` method to remove elements from the end of the array until its size is reduced to `count`. This approach modifies the original array in place. Pros: * Modifying an existing array can be more memory-efficient than creating a new one. * `splice()` can be faster for large arrays, as it only requires updating the internal array pointers. Cons: * `splice()` is generally slower than `slice()` due to its more complex implementation and additional overhead. * It modifies the original array, which might not be desirable in some scenarios. **Test Case 3: shift-while** In this test case, the benchmark uses a while loop to repeatedly remove elements from the beginning of the array until its size is reduced to `count`. This approach also modifies the original array in place. Pros: * Using a while loop can be more memory-efficient than creating or modifying an existing array. * It allows for easier control over the number of iterations and potential optimizations. Cons: * The use of a while loop can make the code more complex and harder to understand. * It might not be as efficient as other approaches, especially for small arrays. **Library and Special JS Features** In this benchmark, no libraries are used. However, JavaScript engines like V8 (used by Chrome) and SpiderMonkey (used by Firefox) have their own optimizations and features that can affect the performance of these methods. There are no special JavaScript features used in this benchmark beyond what's standard in the language. **Other Alternatives** Some alternative approaches for reducing an array size include: * Using `Array.prototype.filter()` to create a new array with only the desired elements. * Utilizing `Array.prototype.reduce()` to accumulate the removed elements into a separate array or data structure. * Employing a custom implementation using bit manipulation and bitwise operations. These alternatives might offer performance benefits for specific use cases, but they may come with additional complexity and overhead.
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