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Array clone
(version: 0)
Comparing performance of:
spread vs slice
Created:
7 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var arr = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20];
Tests:
spread
const arr2 = [...arr];
slice
const arr3 = arr.slice(0);
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
spread
slice
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
gemma2:9b
, generated one year ago):
This benchmark on MeasureThat.net compares different ways to create a copy of an array in JavaScript. **Options Compared:** * **Spread Operator (`...arr`)**: This method uses the spread operator to create a new array containing all elements from the original `arr`. Syntax: `const arr2 = [...arr];` * **Slice Method (`arr.slice(0)`)**: This method creates a shallow copy of the array by taking a slice of its elements from index 0 (the beginning) to the end. Syntax: `const arr3 = arr.slice(0);` **Pros and Cons:** | Approach | Pros | Cons | |--------------|------------------------------------------|-----------------------------------| | Spread Operator | * Cleaner syntax, more concise code. * Works well with nested arrays. | * Can be slightly slower than `slice`. | | Slice Method | * Often slightly faster in performance. | * Less intuitive for beginners. | **Other Considerations:** * **Shallow Copy:** Both methods create *shallow copies*. This means that if the original array contains objects, modifying those objects within the copy will also modify the originals. * **Performance:** While `slice` is often slightly faster, the performance difference is usually not significant in most practical scenarios. The best choice often depends on code readability and personal preference. **Alternatives:** * **JSON.parse(JSON.stringify(arr))**: This method serializes the array to JSON and then parses it back, effectively creating a deep copy. It's generally slower than `slice` or the spread operator but ensures that nested objects are also copied independently. * **Lodash/Underscore Libraries:** These libraries offer specialized functions like `_.cloneDeep()` which create deep copies of arrays. They can be convenient for handling complex data structures. Let me know if you have any more questions about this benchmark or other JavaScript performance topics!
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