Benchmark: Arrays into Object, reduce vs for

Script Preparation code:

var ppl = []
for(var i=0; i<10000; i++) {
	ppl.push({ id: i, name: i+"" }) 
}

Tests:

reduce
var byId = ppl.reduce((stored, current) => ({ ...stored, [current.id]: current }), {});
forcycle
var byId = {} for(var i=0;i<ppl.lenght;i++) { byId[ppl[i].id] = ppl[i] }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce
forcycle

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 what's being tested in the provided JSON.

**Benchmark Definition**

The benchmark measures the performance difference between two approaches for converting an array of objects into an object with the same structure, but using different methods: `reduce()` and a traditional `for` loop.

**Options Compared**

1. **Reduce()**: Uses the `Array.prototype.reduce()` method to iterate over the array of objects and create a new object with the required structure.
2. **For Loop (forcycle)**: Uses a traditional `for` loop to iterate over the array of objects and create a new object with the required structure.

**Pros and Cons**

* **Reduce()**:
	+ Pros:
		- More concise and expressive code.
		- Less error-prone, as it eliminates the need for manual indexing and indexing operations.
	+ Cons:
		- May have higher overhead due to function call and object creation.
		- Can be slower for very large datasets or complex objects.
* **For Loop (forcycle)**:
	+ Pros:
		- Typically faster and more efficient for large datasets or complex objects.
		- More control over the iteration process, which can lead to better performance in certain scenarios.
	+ Cons:
		- Requires manual indexing and indexing operations, which can increase error-prone code.

**Library Used**

None of the methods use a specific library, but `reduce()` is a built-in method provided by the JavaScript language itself. However, if we consider the purpose of the library-like approach in the `for` loop (i.e., creating an object with dynamic keys), one might argue that it's similar to using a library like Lodash or Ramda for working with objects.

**Special JS Feature/Syntax**

The benchmark uses `const` and `var` declarations, which are part of the ECMAScript 5 specification. The use of template literals (e.g., `${i+\"\"}`) is also present in both code snippets.

**Other Alternatives**

If you're interested in exploring other approaches for converting arrays to objects, here are a few alternatives:

1. **Spread operator**: You can use the spread operator (`{ ... }`) with object destructuring to create a new object with dynamic keys.
2. **Object.fromEntries()**: This method was introduced in ECMAScript 2015 and allows you to create an object from an array of key-value pairs using `Array.prototype.map()` or other array methods.
3. **Array.prototype.forEach()**: You can use the `forEach` method to iterate over the array of objects and create a new object with dynamic keys.

Here's an example of how the spread operator could be used:

```javascript
var byId = {};
ppl.forEach((person) => {
  byId[person.id] = person;
});
```

And here's an example using `Object.fromEntries()`:

```javascript
var byId = Object.fromEntries(ppl.map((person) => [person.id, person]));
```

Related benchmarks:

Arrays into Object, reduce vs for (version: 0)

https://www.youtube.com/watch?v=5nzBDkH9lWI

Comparing performance of: reduce vs forcycle

Created: 5 years ago by: Guest

Jump to the latest result

reduce

forcycle

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):