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Spread vs Slice operators in JS
(version: 0)
Comparison between Spread ([...array]) vs slice (array.slice()) operators on an array containing 1,000,000 items.
Comparing performance of:
Spread operator vs Slice operator
Created:
2 years ago
by:
Guest
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Tests:
Spread operator
const array = Array(1000000).fill(42); const array_copy = [...array];
Slice operator
const array = Array(100000).fill(0); const array_copy = array.slice();
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Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
Spread operator
Slice operator
Fastest:
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Slowest:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks! **What is being tested?** The provided JSON represents two individual test cases: "Spread operator" and "Slice operator". The benchmark tests how fast the JavaScript engine can create a copy of an array using either the spread operator (`[...array]`) or the slice operator (`array.slice()`). **Options compared:** * **Spread operator**: `[...array]` + Pros: - More concise and expressive way to create a new array from an existing one. - Can be faster in some cases due to its optimized implementation in modern JavaScript engines. + Cons: - May have performance overhead due to the creation of a new array object. - Can lead to memory allocation issues if not handled carefully. * **Slice operator**: `array.slice()` + Pros: - More traditional and widely supported way to create a new array from an existing one. - Easy to understand and use for developers who are familiar with it. + Cons: - Can be slower than the spread operator due to its more complex implementation. - May lead to more memory allocations if not handled carefully. **Library usage:** There is no library explicitly mentioned in the benchmark definition or test cases. However, it's worth noting that modern JavaScript engines often optimize array operations under the hood, so the actual performance difference between these two approaches may be negligible in most cases. **Special JS feature/syntax:** The benchmark uses JavaScript's spread operator (`[...array]`) and slice operator (`array.slice()`), which are both standard features of the language. However, it's worth mentioning that some older browsers or environments might not support these features natively, so the results may vary depending on the target audience. **Other alternatives:** If you wanted to compare other array copying methods, you could consider the following options: * Using `Array.prototype.slice.call()` or `Array.prototype.slice.apply()`: These methods create a new array by calling the slice method on an existing array. * Using `Array.from(array)`: This method creates a new array from an existing iterable (like an array). * Using a custom implementation with loops: You could write a custom function to iterate over the original array and push each element into a new array. Keep in mind that these alternatives might have different performance characteristics, so it's essential to test them thoroughly if you're considering using them in your benchmark.
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