Benchmark: benchmark for time Array access vs Object access 2

Script Preparation code:

var items = Array.from(Array(100), (_, x) => ({
    key: x,
    value: x * 10
}));

var objContainer = {};
var arrContainer = [];

for (let i = 0; i <= 100; ++i) {
    const item = items[i];
    objContainer[i] = item;
    arrContainer.push(item);
}

Tests:

Array
items.forEach((_, idx) => arrContainer[idx])
Object
items.forEach((_, idx) => objContainer[idx])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array
Object

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36

Browser/OS: Chrome 121 on Linux

View result in a separate tab

Test name	Executions per second
Array	178695.6 Ops/sec
Object	179546.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested, compared, and their pros and cons.

**Benchmark Overview**

The benchmark compares the performance of accessing elements in an array versus an object using JavaScript. The script preparation code creates two containers: `objContainer` (an object) and `arrContainer` (an array). It then populates both containers with 100 items, where each item has a unique key-value pair.

**Test Cases**

There are two test cases:

1. **Array**: The benchmark definition uses the `forEach` method to iterate over the array, accessing elements using their index (`idx`). This is equivalent to using `arrContainer[idx]`.
2. **Object**: Similarly, this test case uses `forEach` to iterate over the object, accessing elements using their key (`idx`). This is equivalent to using `objContainer[idx]`.

**Comparison**

The benchmark compares the performance of these two approaches on an object and an array.

**Pros and Cons**

* **Array Access**
	+ Pros:
		- Typically faster for arrays because indexes are numerical and can be directly accessed.
		- Less overhead compared to accessing objects, as there's no need to look up keys using `in` or bracket notation (`[]`).
	+ Cons:
		- Limited to numerical indexes; if you need to access elements by non-numerical key (e.g., string), this approach won't work.
* **Object Access**
	+ Pros:
		- More flexible and can be used for accessing elements by any type of key, including strings, numbers, or even other objects.
	+ Cons:
		- Typically slower due to the overhead of looking up keys in an object.

**Library/Functionality**

There is no explicit library being used here, but `forEach` is a built-in JavaScript method. If you were to use a third-party library for similar functionality, it might be a polyfill or an alternative implementation that provides better performance or additional features.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntax being tested in this benchmark. However, if we consider the `forEach` loop as a whole, it's using a modern JavaScript feature (`for...of` loops were introduced in ECMAScript 2015).

Related benchmarks:

benchmark for time Array access vs Object access 2 (version: 0)

Comparing performance of: Array vs Object

Created: 2 years ago by: Guest

Jump to the latest result

Array

Object

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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