Benchmark: map vs fromentries

Tests:

map
const x = {...[{id:1,name:'a'},{id:2,name:'b'},{id:3,name:'c'}].reduce((map, item) => map.set(item.id, item.name), new Map())}
fromentries
const x = Object.fromEntries([{id:1,name:'a'},{id:2,name:'b'},{id:3,name:'c'}].map((item) => [item.id, item.name]))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
map
fromentries

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the provided benchmark and explain what's being tested, compared, and some pros and cons of each approach.

**Benchmark Overview**

The provided benchmark is comparing the performance of two JavaScript methods: `Array.prototype.map()` and `Object.fromEntries()`. Both methods are used to transform an array of objects into a new object with the desired structure.

**Test Cases**

There are two test cases:

1. `map`:
```javascript
const x = {...[{id:1,name:'a'},{id:2,name:'b'},{id:3,name:'c'}].reduce((map, item) => map.set(item.id, item.name), new Map())}
```
This code uses the `Array.prototype.reduce()` method to iterate over an array of objects and create a new Map object with the desired structure. The `map` function is then used to transform each value in the Map object.

2. `fromentries`:
```javascript
const x = Object.fromEntries([{id:1,name:'a'},{id:2,name:'b'},{id:3,name:'c'}].map((item) => [item.id, item.name]))
```
This code uses the `Array.prototype.map()` method to transform each value in an array of objects into an array of key-value pairs. The `Object.fromEntries()` method is then used to create a new object from these key-value pairs.

**Library/Dependency**

Neither test case relies on any external libraries or dependencies, making them self-contained and easy to run.

**Special JavaScript Features/Syntax**

Both test cases use the `const` keyword for variable declarations and the spread operator (`...`) to create objects. However, it's worth noting that the `fromEntries()` method is a relatively new feature introduced in ECMAScript 2019 (ES10).

**Pros and Cons of Each Approach**

1. **map()**
	* Pros:
		+ Widely supported across browsers and Node.js versions.
		+ Can be used with other methods, such as `forEach()` or `filter()`.
	* Cons:
		+ Requires the creation of an intermediate object (the Map) to store the transformed data.
		+ May not be as efficient for large datasets due to memory allocation and garbage collection overhead.
2. **fromEntries()**
	* Pros:
		+ More concise and readable than `map()` + `Object.fromEntries()`.
		+ Efficiently creates a new object without requiring intermediate storage.
	* Cons:
		+ Less widely supported across older browsers and Node.js versions (ES10 requires).
		+ May not be as performant for very large datasets due to the overhead of creating a new object.

**Other Alternatives**

If you need to compare performance with even more approaches, consider using:

1. `reduce()` without the spread operator: This would involve creating an array and then iterating over it in the reduction function.
2. Other libraries or frameworks that provide optimized implementations for these methods (e.g., Lodash).

Keep in mind that this benchmark is focused on comparing two specific methods (`map()` and `fromEntries()`). If you need to explore other options, consider adding more test cases or modifying the existing ones to incorporate different approaches.

Related benchmarks:

map vs fromentries (version: 0)

Comparing performance of: map vs fromentries

Created: 5 years ago by: Guest

Jump to the latest result

map

fromentries

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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