Benchmark: Object.fromEntries vs for at scale

Script Preparation code:

var data = { ...Array.from(Array(100).keys()) };

Tests:

Object.fromEntries at scale
for (let i = 0; i < 100000; i++) { Object.fromEntries(Object.entries(data).map((key, value) => [key, value])); }
for at scale
for (let i = 0; i < 100000; i++) { const entries = Object.entries(data); const result = {} for (let i = 0; i < entries.length; i++) { result[entries[i][0]] = entries[i][1]; } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.fromEntries at scale
for at scale

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/117.0.0.0 Safari/537.36

Browser/OS: Chrome 117 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Object.fromEntries at scale	0.3 Ops/sec
for at scale	3.4 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 Overview**

The provided JSON represents a benchmark on the website MeasureThat.net, which compares the performance of two approaches: `Object.fromEntries` and a manual loop using `Object.entries`. The test measures how many times each approach can execute 100,000 iterations in a second.

**Options Compared**

There are only two options being compared:

1. **`Object.fromEntries`**: This method was introduced in ECMAScript 2019 (ES10) and is used to create an object from key-value pairs.
2. **Manual Loop using `Object.entries`**: This approach uses the `Object.entries` method to get an array of key-value pairs, then iterates over it to build a new object.

**Pros and Cons**

Here's a brief overview of each approach:

1. **`Object.fromEntries`**:
	* Pros: concise, readable, and efficient.
	* Cons: may have some overhead due to the creation of an intermediate array, which can be garbage collected.
2. **Manual Loop using `Object.entries`**:
	* Pros: more control over the iteration process, potentially leading to better performance in certain cases (e.g., when handling large datasets).
	* Cons: less readable and concise compared to `Object.fromEntries`.

In general, `Object.fromEntries` is a good choice when you need to create an object from key-value pairs in most modern JavaScript environments. The manual loop using `Object.entries` may be preferred in certain edge cases or when working with legacy browsers.

**Library**

None of the provided test cases use any libraries. They rely solely on built-in JavaScript methods and syntax.

**Special JS Features or Syntax**

There are no special features or syntax mentioned in the benchmark definition or test cases. The focus is on comparing two basic approaches to create an object from key-value pairs.

**Other Alternatives**

If you were to extend this benchmark, you could consider adding more options, such as:

* Using `Array.prototype.reduce()` instead of a manual loop.
* Comparing the performance of `Object.fromEntries` with other polyfills or transpiled versions (e.g., for older browsers).
* Adding more test cases with varying input sizes or types (e.g., objects with nested properties).

By exploring these alternatives, you could gain a better understanding of the trade-offs involved in different approaches to creating objects from key-value pairs.

Related benchmarks:

Object.fromEntries vs for at scale (version: 0)

Comparing performance of: Object.fromEntries at scale vs for at scale

Created: one year ago by: Guest

Jump to the latest result

Object.fromEntries at scale

for at scale

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):