Benchmark: reduce object vs object.fromentries (1K records)

Script Preparation code:

const array = Array.from({ length: 1000 }, (_, i) => ({ key: `key${i}`, value: i }));

Tests:

reduce
function reduce() { return array.reduce((acc, { key, value }) => { acc[key] = value; return acc; }, {}); }
Object.fromEntries
function objectFromEntries() { return Object.fromEntries(array.map(({ key, value }) => [key, value])); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce
Object.fromEntries

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36 Edg/127.0.0.0

Browser/OS: Chrome 127 on Windows

View result in a separate tab

Test name	Executions per second
reduce	171484560.0 Ops/sec
Object.fromEntries	194263264.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark is defined by two JavaScript functions: `reduce` and `objectFromEntries`. Both functions are designed to process an array of objects with key-value pairs. The main difference between them lies in how they create and manipulate the resulting object.

**Reduce Function**

The `reduce` function takes an initial value (`{}`) and iterates through the array, accumulating values into the accumulator (`acc`). In this implementation, each object in the array is assigned to a property of the accumulator, effectively creating a new object with the key-value pairs. The resulting object is then returned.

**Object.fromEntries Function**

The `objectFromEntries` function uses the `Object.fromEntries()` method, which creates a new object from an iterable (in this case, an array of key-value pairs). This approach is more concise and modern than the `reduce` function.

**Comparison**

The benchmark compares the performance of these two approaches:

*   **Reduce Function**: This implementation has a higher memory overhead due to the need to create an accumulator object for each iteration. It also involves more explicit operations, which can be slower.
*   **Object.fromEntries Function**: This approach is often faster and more efficient because it leverages the optimized `Object.fromEntries()` method.

**Pros and Cons**

**Reduce Function:**

Pros:

*   Easy to understand for developers familiar with array iteration
*   Can be used in scenarios where the resulting object needs to be iterated over further

Cons:

*   Higher memory overhead due to accumulator object creation
*   Less concise than the `objectFromEntries` function

**Object.fromEntries Function:**

Pros:

*   Faster and more efficient, thanks to optimized implementation
*   More concise and readable code

Cons:

*   May be less familiar or intuitive for developers without experience with modern JavaScript features
*   Not all browsers support `Object.fromEntries()` (though it's widely supported)

**Library Usage**

In this benchmark, there is no explicit library usage. However, the `Array.from()` method used in both implementations relies on the built-in `Array.prototype.from()` method, which is part of the JavaScript standard library.

**Special JS Features/Syntax**

There are no specific JavaScript features or syntax mentioned in this benchmark that would require a deeper understanding of advanced topics like closures, async/await, or modern JavaScript paradigms. The code focuses on basic array manipulation and object creation using modern methods.

**Alternatives**

If you're looking for alternatives to these two approaches, consider the following:

*   **For loops**: You can use traditional `for` loops with index iteration to create an object from an array of key-value pairs.
*   **Spread operators**: Another approach is to use the spread operator (`{...}`) to create a new object and then iterate through the array, assigning values to properties.
*   **Array.prototype.map()** + **Object.assign()**: You can also use `array.map()` to transform an array into an array of key-value pairs and then pass it to `Object.assign()` to create a new object.

Keep in mind that each approach has its trade-offs in terms of performance, readability, and maintainability.

Related benchmarks:

reduce object vs object.fromentries (1K records) (version: 0)

Comparing performance of: reduce vs Object.fromEntries

Created: one year ago by: Guest

Jump to the latest result

reduce

Object.fromEntries

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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