Benchmark: Object.fromEntries vs reduce - no map v2

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.toString(); return acc; }, {});
Reduce (creating temporary objects)
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:

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

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:103.0) Gecko/20100101 Firefox/103.0

Browser/OS: Firefox 103 on Linux

View result in a separate tab

Test name	Executions per second
Object.fromEntries	4444.6 Ops/sec
Reduce (reuse object)	1558.8 Ops/sec
Reduce (creating temporary objects)	0.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and their pros/cons.

**Benchmark Description**

The test case compares three approaches for creating an object from an array of key-value pairs:

1. `Object.fromEntries(data)`: This method creates a new object by iterating over the input array and adding each key-value pair to the object.
2. `data.reduce((acc, [k, v]) => {...}, {})`: This method uses the reduce() function to create an accumulator object, which is then iterated over to add each key-value pair.
3. The third approach is not explicitly specified in the benchmark definition, but it's implied to be creating a temporary object using `reduce()` with a more complex callback.

**Comparison**

The three approaches are compared in terms of their execution time on a specific browser (Firefox 103) and device platform (Desktop Linux).

**Approach 1: `Object.fromEntries(data)`**

This approach creates a new object by iterating over the input array. The pros of this method include:

* It's concise and easy to read.
* It doesn't require any additional memory allocation, as it returns a new object.

However, there are some potential cons:

* It may be slower than the other approaches due to the overhead of creating a new object.
* It requires at least one extra function call (to `Object.entries()`).

**Approach 2: `data.reduce((acc, [k, v]) => {...}, {})`**

This approach uses the reduce() function to create an accumulator object. The pros of this method include:

* It's often considered more efficient than creating a new object, as it reuses existing memory.
* However, it may require additional memory allocation for the accumulator object.

However, there are some potential cons:

* The callback function is more complex and harder to read.
* It requires at least one extra variable (the accumulator `acc`).

**Approach 3: Creating a temporary object**

This approach is not explicitly specified in the benchmark definition, but it's implied to be creating a temporary object using `reduce()` with a more complex callback. The pros of this method include:

* It reuses existing memory, just like Approach 2.
* However, it may require additional memory allocation for the temporary object.

However, there are some potential cons:

* The callback function is even more complex and harder to read than in Approach 2.
* It requires at least one extra variable (the temporary object).

**Library: `Array.prototype.entries()`**

The `Array.prototype.entries()` method returns an array of key-value pairs from the input array. In this benchmark, it's used to convert the input array into a format that can be passed to `Object.fromEntries()`. The pros of using this method include:

* It's concise and easy to read.
* However, there are some potential cons:
	+ It may not work as expected if the input array is modified after calling `Array.prototype.entries()`.

**Other Considerations**

There are other factors that can affect the performance of these approaches, such as:

* The size and complexity of the input data.
* The specific JavaScript engine and version being used.
* Other concurrent tasks or memory usage on the system.

As for special JS features or syntax, there aren't any mentioned in this benchmark. However, if you're interested in exploring other approaches or optimizations, some additional options might include:

* Using `Array.prototype.forEach()` instead of `reduce()`.
* Creating a temporary array using `Array.prototype.map()` and then passing it to `Object.fromEntries()`.
* Optimizing the input data structure or processing pipeline.

Keep in mind that these alternative approaches may have different trade-offs in terms of performance, readability, and memory usage.

Related benchmarks:

Object.fromEntries vs reduce - no map v2 (version: 0)

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

Created: 4 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 2 months ago):