Benchmark: Reduce vs Object.assign vs Object.fromEntries

Script Preparation code:

function createArray(propsCount) {
    const arr = []
    for (let i = 0; i < propsCount; i += 1) {
        arr.push({
            active: i % 5 === 0
        })
    }
    return arr
}

var users = createArray(1000)

Tests:

Reduce
users.reduce((acc, curr) => { if (curr.active) { return acc } return { ...acc, [curr.id]: curr.name } })
Map Filter Reduce Assign
users.filter((user) => !user.active).map((user) => ({ [user.id]: user.name })).reduce(Object.assign, {})
From Entries
const a = users.filter((user) => !user.active).map((user) => [user.id, user.name]) Object.fromEntries(a)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Reduce
Map Filter Reduce Assign
From Entries

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The benchmark is designed to compare three different approaches for performing a common JavaScript operation:

1. `Object.assign()`
2. `Object.fromEntries()` (which was introduced in ECMAScript 2017)
3. Using the `reduce()` method with an accumulator object

These three approaches are compared in the following test cases:

* `Map Filter Reduce Assign`: This test case uses a combination of `filter()`, `map()`, and `reduce()` methods, as well as `Object.assign()`.
* `From Entries`
* `Reduce`

**Options Compared**

The benchmark compares the performance of three different approaches:

1. `Object.assign()`: A simple object assignment method that creates a new object by copying properties from an existing object.
2. `Object.fromEntries()`: A method that creates a new object from an array of key-value pairs.
3. Using the `reduce()` method with an accumulator object: This approach uses the `reduce()` method to iterate over an array and accumulate values in an object.

**Pros and Cons**

Here are some pros and cons for each approach:

1. **`Object.assign()`**:
	* Pros: Simple, widely supported, and easy to read.
	* Cons: Can be slow for large datasets, as it creates a new object by copying properties from an existing object.
2. **`Object.fromEntries()`**:
	* Pros: Efficient, modern method that was introduced in ECMAScript 2017.
	* Cons: May not be supported in older browsers or environments.
3. **Reduce with accumulator object**:
	* Pros: Can be efficient for large datasets, as it avoids creating a new object by copying properties from an existing object.
	* Cons: Requires understanding of the `reduce()` method and its accumulator parameter.

**Library and Purpose**

None of the libraries are explicitly mentioned in the benchmark definition. However, `Object.fromEntries()` is a built-in JavaScript method that was introduced in ECMAScript 2017.

**Special JS Features or Syntax**

The `Map Filter Reduce Assign` test case uses some advanced JavaScript features, including:

1. **Array methods**: `filter()`, `map()`, and `reduce()` are used to process the data.
2. **Object assignment**: `Object.assign()` is used in one of the test cases.

These features are widely supported in modern browsers and environments, but may not be understood by older developers or those without experience with these methods.

**Alternatives**

If you're looking for alternative approaches or want to explore other options, here are a few suggestions:

1. Using `lodash` library: Lodash provides an implementation of the `assign()` method that can be faster than the built-in `Object.assign()`.
2. Using `merge()` method from `lodash`: Similar to `Object.assign()`, but with some performance improvements.
3. Using `reduce()` method with a custom accumulator object: This approach can be efficient for large datasets, but requires understanding of the `reduce()` method and its accumulator parameter.

It's worth noting that these alternatives may not provide significant performance improvements over the original benchmark, as they are often implemented in native code or have been optimized for performance.

Latest run results:

Run details: (Test run date: 11 hours ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Linux

View result in a separate tab

Test name	Executions per second
Reduce	23376.0 Ops/sec
Map Filter Reduce Assign	21.6 Ops/sec
From Entries	27778.2 Ops/sec

Related benchmarks:

Reduce vs Object.assign vs Object.fromEntries (version: 0)

Comparing performance of: Reduce vs Map Filter Reduce Assign vs From Entries

Created: 3 years ago by: Guest

Jump to the latest result

Reduce

Map Filter Reduce Assign

From Entries

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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