Benchmark: Object.fromEntries vs reduce2

Script Preparation code:

var data = Object.entries({ ...Array.from(Array(10000).keys()) });

Tests:

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

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:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:100.0) Gecko/20100101 Firefox/100.0

Browser/OS: Firefox 100 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
Object.fromEntries	4876.6 Ops/sec
Reduce (reuse object)	2345.0 Ops/sec
Reduce (creating temporary objects)	0.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

The provided JSON represents a benchmark for comparing three approaches to create an object from an array of key-value pairs:

1. `Object.fromEntries`
2. `Array.prototype.reduce` with reuse of an accumulator object
3. `Array.prototype.reduce` with creation of temporary objects

**Options Compared**

* **Approach 1: `Object.fromEntries`**
	+ Pros:
		- Easy to read and write, as it resembles the `Map constructor`.
		- Efficient, as it avoids creating intermediate objects.
	+ Cons:
		- May not be optimized for performance in older browsers or with certain configurations.
* **Approach 2: Reuse of accumulator object**
	+ Pros:
		- Can be faster than Approach 1 due to reduced object creation overhead.
		- Still efficient, as it avoids creating intermediate objects.
	+ Cons:
		- Requires more code and might lead to slightly slower execution times for some developers.
* **Approach 3: Creating temporary objects**
	+ Pros:
		- Simple and straightforward implementation.
	+ Cons:
		- Creates unnecessary temporary objects, which can be slow due to object creation overhead.

**Other Considerations**

* The benchmark uses a fixed dataset (`Array.from(Array(10000).keys())`) to ensure consistent results across different browsers and configurations.
* It's worth noting that the `Object.fromEntries` method is relatively new (introduced in ECMAScript 2015) and may not be supported in older browsers.

**Library**

None of the test cases use a specific library, as they only rely on built-in JavaScript methods.

**Special JS Feature/Syntax**

* The `Map constructor` is used implicitly when creating an object with `Object.fromEntries`, which is a more concise way to create objects than using `Array.prototype.reduce`. This feature was introduced in ECMAScript 2015.
* The `reduce()` method is used extensively in the benchmark, as it's a common pattern for iterating over arrays and accumulating values.

**Other Alternatives**

For creating an object from an array of key-value pairs, other alternatives to these three approaches include:

1. `Array.prototype.forEach()` with explicit loops
2. `String.prototype.split()` and `Object.assign()`
3. Using a library like Lodash (`_.mapKeys()`, `_.reduce()`) or Ramda (`R.mapKeys()`, `R.reduce`)

Keep in mind that these alternatives may have different performance characteristics, readability, and complexity compared to the three approaches tested in this benchmark.

Overall, the benchmark provides valuable insights into the performance differences between various JavaScript methods for creating objects from arrays of key-value pairs.

Related benchmarks:

Object.fromEntries vs reduce2 (version: 0)

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

Created: 2 years ago by: Guest

Jump to the latest result

Object.fromEntries

Reduce (reuse object)

Reduce (creating temporary objects)

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):