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test spread in reduce
(version: 0)
Comparing performance of:
mutable vs immutable
Created:
7 years ago
by:
Guest
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Tests:
mutable
[...Array(10).keys()].reduce((acc, val) => { acc[val] = val; return acc; }, {})
immutable
[...Array(10).keys()].reduce((acc, val) => { return { ...acc, [val]: val }; }, {})
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Suite status:
<idle, ready to run>
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Test case name
Result
mutable
immutable
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**What is being tested?** The provided benchmark measures the performance difference between two approaches to modify an object using the `reduce()` method in JavaScript. In the first approach, called "mutable", the accumulator (`acc`) is modified directly by assigning new values to its properties (`acc[val] = val`). In contrast, the second approach, labeled as "immutable", creates a new object by spreading the current state of the accumulator (`{ ...acc, [val]: val }`) and then assigns this new object to the accumulator. **Options compared** The benchmark compares two different approaches: 1. **Mutable**: Directly modifying the accumulator object using its properties. 2. **Immutable**: Creating a new object by spreading the current state of the accumulator and then assigning it to the accumulator. **Pros and Cons of each approach:** **Mutable Approach:** Pros: * Often more intuitive and straightforward * Can be faster due to fewer object allocations Cons: * Modifies the original object, which may have unintended consequences * May lead to performance issues if the object is large or complex **Immutable Approach:** Pros: * Preserves the original state of the accumulator * Avoids potential side effects and unintended modifications Cons: * May be slower due to additional object allocations * Requires careful consideration when dealing with complex objects **Other considerations:** * **Object Allocation**: The immutable approach requires creating a new object for each iteration, which can lead to increased memory allocation and garbage collection overhead. * **Cache Locality**: In some cases, the mutable approach may exhibit better cache locality due to direct access to the accumulator's properties. **Library usage:** None of the provided benchmark definitions explicitly use any external libraries. However, it is likely that the underlying JavaScript engine (e.g., V8) uses various internal libraries and optimizations that might impact the benchmark results. **Special JS features or syntax:** No special JavaScript features or syntax are used in these benchmark definitions. The code follows standard JavaScript syntax and semantics. **Alternative approaches:** Other approaches to modifying an object using `reduce()` could include: 1. Using `forEach()` instead of `reduce()` 2. Utilizing library functions like Lodash's `map()` and `assign()` 3. Employing more complex data structures, such as arrays or objects with nested properties These alternative approaches may offer different trade-offs in terms of performance, readability, and maintainability.
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