Benchmark: Object.fromEntries vs reduce vs Map + Array.from

Script Preparation code:

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

Tests:

Object.fromEntries
Object.fromEntries(Object.entries(data).map((key, value) => [key, value]));
Reduce (reuse object)
Object.entries(data).reduce((acc, [k, v]) => { acc[k] = v.toString(); return acc; }, {});
Map + Array.from
Array.from(new Map(Object.entries(data).map((key, value) => [key, value])))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.fromEntries
Reduce (reuse object)
Map + Array.from

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 4 days ago):

LLMs can make mistakes. Check important info.

**Overview**

The provided JSON represents a JavaScript benchmark test case on MeasureThat.net, which compares the performance of three different approaches to create an object from key-value pairs: `Object.fromEntries`, `reduce`, and `Map + Array.from`.

**Approaches Compared**

1. **`Object.fromEntries`**: This method creates an object from an array of key-value pairs. It's a relatively new addition to JavaScript, introduced in ECMAScript 2019 (ES10).
2. **`reduce`**: The `reduce` method applies a function to each element in an array and reduces it to a single value. In this case, it's used to create an object from key-value pairs by accumulating the values in an object.
3. **`Map + Array.from`**: This approach uses a `Map` data structure to store key-value pairs and then converts it to an array using `Array.from`. The array is then passed to `Object.fromEntries`.

**Pros and Cons of Each Approach**

1. **`Object.fromEntries`**:
	* Pros: High performance, concise syntax, widely supported (ES10+).
	* Cons: May not be optimized for older browsers or environments without ES10 support.
2. **`reduce`**:
	* Pros: Widely supported, flexible syntax.
	* Cons: Can be slower than `Object.fromEntries`, especially with large arrays.
3. **`Map + Array.from`**:
	* Pros: May offer better performance in older browsers or environments without ES10 support, as it avoids the overhead of `Object.fromEntries`.
	* Cons: More verbose syntax, requires additional data structure creation.

**Library and Special JS Features**

In this benchmark, no external libraries are used. However, note that `Map` is a built-in JavaScript data structure introduced in ECMAScript 1999 (ES3), so it's not specific to modern browsers or environments.

There are no special JavaScript features being tested here, as the approaches are relatively standard and widely supported.

**Other Alternatives**

In addition to these three approaches, other methods for creating objects from key-value pairs include:

1. **`Object.keys()` + `reduce()`**: This approach uses `Object.keys()` to get an array of keys and then reduces it to an object using the `reduce()` method.
2. **`Array.prototype.reduce()`**: Similar to the previous approach, but uses `Array.prototype.reduce()` instead.
3. **Manual iteration**: Creating an object by manually iterating over key-value pairs using a loop.

These alternatives may have different performance characteristics compared to the approaches tested in this benchmark.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 11_2_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.182 Safari/537.36

Browser/OS: Chrome 88 on Mac OS X 11.2.1

View result in a separate tab

Test name	Executions per second
Object.fromEntries	144.9 Ops/sec
Reduce (reuse object)	956.8 Ops/sec
Map + Array.from	525.2 Ops/sec

Related benchmarks:

Object.fromEntries vs reduce vs Map + Array.from (version: 0)

Comparing performance of: Object.fromEntries vs Reduce (reuse object) vs Map + Array.from

Created: 3 years ago by: Guest

Jump to the latest result

Object.fromEntries

Reduce (reuse object)

Map + Array.from

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 4 days ago):