Benchmark: benchmark for time Array access vs Object access for loop

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
for (let i = 0; i < items.length; ++i) arrContainer[i];
Object
for (let i = 0; i < items.length; ++i) objContainer[i];

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	95784.2 Ops/sec
Object	93949.1 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided JSON and explain what's being tested, compared, and other considerations.

**Benchmark Overview**

The benchmark is designed to compare the performance of accessing an array versus an object using a for loop. The script preparation code creates two containers: `objContainer` (an object) and `arrContainer` (an array). It then populates these containers with 100 items each, where each item has a unique key and value.

**Options Compared**

The benchmark compares the performance of accessing an element in an array (`items[i]`) versus an object (`objContainer[i]`). The same loop is used for both cases, and the time taken to execute the loop is measured.

**Pros and Cons**

* **Array Access**: This approach is likely faster because arrays are optimized for random access. In JavaScript, arrays store elements in contiguous memory locations, making it easier to jump directly to a specific element using its index.
* **Object Access**: Objects, on the other hand, store properties as key-value pairs, which can lead to slower performance due to the overhead of searching for a property using its key.

**Library and Purpose**

The benchmark uses no external libraries. However, it relies on JavaScript's built-in features, such as arrays and objects.

**Special JS Feature or Syntax**

There is no special JavaScript feature or syntax being tested in this benchmark. It's purely focused on comparing the performance of accessing an array versus an object.

**Other Considerations**

* The benchmark uses a simple for loop with a fixed number of iterations (100). More complex loops or larger datasets might affect the results.
* The `items` array is created using `Array.from()` and an arrow function, which can lead to slower performance compared to traditional array creation methods. However, this effect is likely negligible in this specific benchmark.
* The benchmark is run on a desktop platform (Chrome 121) with Linux as the operating system.

**Alternative Benchmarks**

Other benchmarks that might be of interest include:

1. **Array vs Object lookups**: Instead of accessing an element using its index, the benchmark could compare the performance of using a property key to access an object's value.
2. **Array vs Object iteration**: The benchmark could be modified to iterate over arrays and objects using different methods (e.g., `forEach()` vs `.push()`).
3. **Cache-friendly data structures**: The benchmark could explore the performance of accessing elements in cache-friendly data structures, such as SIMD arrays or buffer-like objects.

These alternative benchmarks might provide additional insights into JavaScript's optimization strategies and the trade-offs between different data structures and access patterns.

Related benchmarks:

benchmark for time Array access vs Object access for loop (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):