Benchmark: Object mapping : reduce ( object reuse ) VS. no reuse VS. fromEntries+map

Script Preparation code:

var obj = {
  ...Array.from(Array(10000).keys())
};

Tests:

reduce (object reuse)
Object.entries(obj).reduce((acc, [k, v]) => { acc[k] = v; return acc; }, {});
reduce (no reuse)
Object.entries(obj).reduce((acc, [k, v]) => ({ ...acc, [k]: v, }), {});
fromEntries
Object.fromEntries( Object.entries(obj).map( ([k, v]) => [k, v] ) );

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce (object reuse)
reduce (no reuse)
fromEntries

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmarking test case, where the goal is to compare the performance of three different approaches for object mapping: reducing an object using `Object.entries` and `reduce`, with and without reusing the accumulator.

**Test Cases**

There are three test cases:

1. **"reduce (object reuse)"**: This test case uses the original approach of reducing the object using `Object.entries` and `reduce`, where the accumulator is reused.
2. **"reduce (no reuse)"**: This test case modifies the original approach by not reusing the accumulator, resulting in a new object being created on each iteration.
3. **"fromEntries+map"`: This test case uses a more modern approach of creating an object from an array of key-value pairs using `Object.fromEntries` and mapping over the array to create individual key-value pairs.

**Options Compared**

The three test cases are compared in terms of their performance, measured by the number of executions per second.

**Pros and Cons**

* **"reduce (object reuse)"**: This approach reuses the accumulator, which can lead to better performance due to reduced object creation overhead. However, it may also lead to incorrect results if the accumulator is modified unexpectedly.
* **"reduce (no reuse)"**: This approach creates a new object on each iteration, which can be slower due to object creation overhead. However, it ensures that the result is accurate and predictable.
* **"fromEntries+map"`: This approach uses modern JavaScript features to create an object from an array of key-value pairs. It may provide better performance than the traditional `reduce` approach, but its performance depends on the specific use case.

**Libraries and Features**

None of the test cases use any external libraries or special JS features other than the built-in `Object.entries`, `Object.fromEntries`, and `Array.prototype.map` methods.

**Other Considerations**

* **Object creation overhead**: The performance difference between reusing and not reusing the accumulator can be significant due to object creation overhead.
* **Predictability and accuracy**: Using a reusable accumulator ensures predictability and accuracy, while not reusing it may lead to unexpected behavior or incorrect results.

**Alternatives**

Other alternatives for comparing performance include:

* Using `Object.assign` instead of `reduce`
* Comparing the performance of different JavaScript engines (e.g., V8 vs. SpiderMonkey)
* Adding more test cases with varying input sizes and shapes
* Using a profiling tool to analyze the execution time and memory usage of each approach

Related benchmarks:

Object mapping : reduce ( object reuse ) VS. no reuse VS. fromEntries+map (version: 0)

Comparing performance of: reduce (object reuse) vs reduce (no reuse) vs fromEntries

Created: 5 years ago by: Guest

Jump to the latest result

reduce (object reuse)

reduce (no reuse)

fromEntries

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):