Benchmark: create temp object vs Object.fromEntries #2

Script Preparation code:

var array = Array.from(Array(10000).keys()).map(i => {
    var length = Math.round(Math.random()*100)
    var result           = '';
    var characters       = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    var charactersLength = characters.length;
    for ( var i = 0; i < length; i++ ) {
      result += characters.charAt(Math.floor(Math.random() * 
 charactersLength));
   }
   return result;
})

Tests:

Object.fromEntries
Object.fromEntries(array.map(value => [value, true]));
creating temporary objects
const data = {} array.forEach(value => data[value] = true);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.fromEntries
creating temporary objects

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Object.fromEntries	1586.3 Ops/sec
creating temporary objects	3229.9 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Definition and Script Preparation Code**

The benchmark is designed to measure the performance difference between two approaches:

1. Creating temporary objects using `Array.forEach()`.
2. Using `Object.fromEntries()` with an array created from another array.

The script preparation code generates an array of 10,000 random strings (each string has a length between 1 and 100) and maps over this array to create the following values:

* `result`: an empty string
* `characters`: a fixed string containing all uppercase and lowercase letters, numbers, and special characters
* `charactersLength`: the length of the `characters` string

This script preparation code is executed before running each benchmark.

**Benchmark Preparation Code**

The individual test cases define two benchmarks:

1. **Object.fromEntries()**: creates an object from an array using `Object.fromEntries()` with a mapping function that pairs each value in the array with a boolean value (`true`).
2. **Creating temporary objects**: uses `Array.forEach()` to create temporary objects by assigning `true` values to properties on an empty object.

**Options Compared**

The two approaches differ in how they handle data:

1. **Object.fromEntries()**:
	* Creates a new object with the specified entries.
	* Returns the new object.
	* Does not modify the original array or its elements.
2. **Creating temporary objects**:
	* Uses an empty object as a container.
	* Iterates over the array and assigns values to properties on this object.
	* Modifies the original array by consuming it.

**Pros and Cons**

* **Object.fromEntries()**:
	+ Pros: creates a new object, easy to use, efficient in terms of memory allocation.
	+ Cons: may involve additional overhead due to the creation of an intermediate object (depending on the JavaScript engine).
* **Creating temporary objects**:
	+ Pros: allows for direct manipulation of array elements, potentially faster for large datasets.
	+ Cons: creates an empty object and iterates over the original array, which can be slower than `Object.fromEntries()`.

**Library Usage**

Neither approach uses a specific library. However, some JavaScript engines may optimize or provide better performance for these operations due to their built-in implementation or caching mechanisms (e.g., V8 in Chrome).

**Special JS Feature/Syntax**

The benchmark does not use any special JavaScript features or syntax that would require an in-depth explanation.

**Other Alternatives**

If you're interested in exploring other approaches, here are some alternatives:

1. **Using `reduce()`**: Instead of using `Array.forEach()`, you could use the `reduce()` method to create a new object from the array.
2. **Using `map()` with an object literal**: Similar to `Object.fromEntries()`, but without the explicit mapping function.

Here's an example of how you could modify the second test case to use `reduce()`:

```javascript
const data = {};
array.reduce((acc, value) => acc[value] = true, {});
```

And here's an example using `map()` with an object literal:

```javascript
const data = {};
array.map(value => ({ [value]: true })).reduce((acc, obj) => Object.assign(acc, obj), {});
```

These alternatives may offer different performance profiles or trade-offs in terms of code readability and maintainability.

Related benchmarks:

create temp object vs Object.fromEntries #2 (version: 0)

Comparing performance of: Object.fromEntries vs creating temporary objects

Created: 3 years ago by: Guest

Jump to the latest result

Object.fromEntries

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):