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In loop, push(...) vs spread v2
(version: 0)
Comparing the various ways to append to a large array during a loop
Comparing performance of:
Control (for push) vs Spread
Created:
3 years ago
by:
Guest
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Script Preparation code:
window.top.tests = {control:[], spread:[]}; window.test = (new Array(100)).fill(null); window.cutoff = 5000;
Tests:
Control (for push)
for (let element of window.test) window.top.tests.control.push(element);
Spread
store = [] for (let element of window.test) window.top.tests.spread = [...store, element]
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
Control (for push)
Spread
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of MeasureThat.net and understand what's being tested in this benchmark. **Benchmark Definition** The benchmark compares two approaches to append elements to an array during a loop: 1. **Control**: Using `push()` method on the array. 2. **Spread**: Using the spread operator (`...`) to create a new array and then appending elements using `push()`. **Options Compared** We have two options being compared: * **Control (for push)**: This approach uses the traditional `push()` method to add elements to the end of an array. The `push()` method modifies the original array by adding one or more values to the end. * **Spread**: This approach creates a new array using the spread operator (`...`) and then appends elements using `push()`. The spread operator creates a shallow copy of an array, allowing us to add new elements while preserving the original array's structure. **Pros and Cons** **Control (for push)** Pros: * Simple and widely supported. * No additional memory allocation is required for creating a new array. Cons: * Can be slower due to the need to modify the original array by adding elements to the end. * May lead to performance issues if the array grows very large, as it requires frequent reallocation of memory. **Spread** Pros: * Creates a shallow copy of the original array, which can help prevent performance issues when dealing with large arrays. * More efficient than `push()` in terms of time complexity (O(1) vs O(n)) for appending elements to the end of an array. Cons: * Requires additional memory allocation for creating a new array. * May lead to performance issues if the spread operator creates too many temporary objects, which can be a concern for very large arrays. **Other Considerations** The benchmark assumes that we're dealing with a large array (`window.test` has 100 elements) and an efficient JavaScript engine (e.g., V8 in Chrome). The choice between `push()` and the spread operator depends on the specific use case, such as performance-critical code or situations where memory allocation is a concern. **Library Used** In this benchmark, we're using the `window.test` array to simulate a large dataset. No external libraries are used beyond the standard JavaScript features (e.g., `push()` and spread operator). **Special JS Feature or Syntax** There's no special JavaScript feature or syntax being tested in this benchmark. However, it's worth noting that modern JavaScript engines often optimize array operations under the hood, so the results might vary depending on the specific engine implementation. **Other Alternatives** If you're interested in exploring other approaches, consider: * Using `concat()` instead of `push()`: While similar to `push()`, `concat()` creates a new array and returns it, whereas `push()` modifies the original array. * Using `Array.prototype.set()` (if supported by your browser): This method allows you to update an existing array in place without creating a new one. Keep in mind that these alternatives might have different performance characteristics or use cases compared to the spread operator and `push()`.
Related benchmarks:
Concat vs push(...) vs spread for large arrays
In loop, push(...) vs spread
Concat vs push(...) for large arrays using spread in test 2
push() vs [...] for large arrays
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