Benchmark: Bars Object.fromEntries vs reduce

Script Preparation code:

var data = { ...Array.from(Array(100).keys()) };

Tests:

Object.fromEntries
Object.fromEntries(Object.entries(data).map((key, value) => [key, value]));
Reduce (reuse object)
Object.entries(data).reduce((acc, [k, v]) => { acc[k] = v.toString(); return acc; }, {});
Reduce (creating temporary objects)
Object.entries(data).reduce((acc, [k, v]) => ({ ...acc, [k]: v.toString() }), {});

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.fromEntries
Reduce (reuse object)
Reduce (creating temporary objects)

Fastest: N/A

Slowest: N/A

Latest run results:

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

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**Overview of the Benchmark**

The provided benchmark measures the performance difference between three approaches for creating an object from an array of key-value pairs: `Object.fromEntries`, `reduce` with reusing an empty object, and `reduce` with creating temporary objects.

**Test Cases**

There are three test cases:

1. **Object.fromEntries**: This method takes an iterable (in this case, the result of `Array.from(Array(100).keys())`) and creates a new object from its entries.
2. **Reduce (reuse object)**: In this approach, an empty object is reused as the accumulator for the reduction. The callback function updates the accumulator with each key-value pair, returning the updated object.
3. **Reduce (creating temporary objects)**: Here, a new object is created for each iteration of the reduction, using the `Object.assign()` method to update its properties.

**Comparison and Analysis**

The main difference between these approaches lies in their memory allocation and object creation patterns:

*   `Object.fromEntries` creates a new object from scratch, which can be slower due to object creation overhead.
*   **Reduce (reuse object)**: This approach reuses the same object for all iterations, reducing memory allocation and garbage collection. However, it can lead to increased memory usage over time if the object grows significantly.
*   **Reduce (creating temporary objects)**: In this case, a new object is created on each iteration, but it's immediately updated by `Object.assign()`. This approach may have some overhead due to function calls and property updates.

**Pros and Cons**

*   **Memory Efficiency**: Reduce (reuse object) is more memory-efficient as it reuses the same object.
*   **Performance Overhead**: Object.fromEntries might be slower due to object creation, while Reduce (creating temporary objects) incurs some overhead from function calls and updates.
*   **Object Growth**: If the object grows significantly in size, Reduce (reuse object) may lead to increased memory usage over time.

**Library and Special JS Features**

None of the test cases explicitly use a library. However, they do utilize the `Array.from()` method, which is a part of the ECMAScript standard since ES6.

**Alternative Approaches**

For creating objects from arrays of key-value pairs, other approaches might include:

*   Using `Object.assign()` and an empty object.
*   Utilizing `Map` data structure (introduced in ES6).
*   Leveraging template literals for more efficient string creation.

Related benchmarks:

Bars Object.fromEntries vs reduce (version: 2)

Comparing performance of: Object.fromEntries vs Reduce (reuse object) vs Reduce (creating temporary objects)

Created: 3 years ago by: Registered User

Jump to the latest result

Object.fromEntries

Reduce (reuse object)

Reduce (creating temporary objects)

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):