Benchmark: _.fromPairs vs Object.fromEntries

HTML Preparation code:

<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>

Tests:

Object.fromEntries
var a = [['a', 1], ['b', 2], ['c', 3]]; var b = Object.fromEntries(a);
_.fromPairs
var a = [['a', 1], ['b', 2], ['c', 3]]; var b = _.fromPairs(a);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.fromEntries
_.fromPairs

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:123.0) Gecko/20100101 Firefox/123.0

Browser/OS: Firefox 123 on Windows

View result in a separate tab

Test name	Executions per second
Object.fromEntries	8251895.5 Ops/sec
_.fromPairs	12006329.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to help you understand the provided benchmark.

**What is being tested?**

The benchmark compares two approaches for creating an object from key-value pairs: `_.fromPairs` (a function from the Ramda library) and `Object.fromEntries` (a built-in JavaScript method).

**Options compared:**

1. **Ramda's _.fromPairs**: This function creates an object from key-value pairs, where each pair is passed as an array of two elements.
2. **JavaScript's Object.fromEntries**: This method creates an object from key-value pairs, where each pair is passed as an iterable (such as an array or a Map).

**Pros and Cons:**

1. **Ramda's _.fromPairs**:
	* Pros:
		+ Simple and concise syntax.
		+ Works with any type of iterable input (not just arrays).
	* Cons:
		+ May have performance overhead due to the need to bind the Ramda library.
2. **JavaScript's Object.fromEntries**:
	* Pros:
		+ Built-in method, so no additional library needed.
		+ Often faster than other approaches since it's optimized by JavaScript engines.
	* Cons:
		+ Syntax can be less readable for some developers, especially those not familiar with the method.

**Other considerations:**

1. **Browser support**: Both methods are supported in modern browsers, but `Object.fromEntries` is more widely supported due to its built-in nature.
2. **Performance**: The benchmark measures executions per second, which indicates the performance difference between the two approaches.

**Library and syntax used:**

The Ramda library provides a simple way to work with functions and data transformations. `_fromPairs` is one of the utility functions provided by Ramda.

**Special JS feature or syntax:**

There are no special features or syntaxes being tested in this benchmark, but it's worth noting that `Object.fromEntries` is a relatively new method introduced in ECMAScript 2017 (ES2017).

**Alternatives:**

Other approaches to creating an object from key-value pairs include:

1. Using the `reduce()` method with an initial value of `{}`:
```javascript
var obj = {};
a.reduce((obj, [key, value]) => ({ ...obj, [key]: value }), obj);
```
2. Using the `Map` constructor and then spreading its entries to create a new object:
```javascript
var map = new Map(a.map(([key, value]) => [key, value]));
var obj = Object.fromEntries(map.entries());
```
3. Manually iterating over the input array and creating an object property for each pair.

These alternatives may have different performance characteristics or requirements (e.g., memory usage), depending on the specific use case and constraints.

Related benchmarks:

_.fromPairs vs Object.fromEntries (version: 0)

Comparing performance of: Object.fromEntries vs _.fromPairs

Created: 5 years ago by: Guest

Jump to the latest result

Object.fromEntries

_.fromPairs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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