Benchmark: Large but empty Array versus Small Object (Access wise)

Script Preparation code:

var indexes = [];
var array = [];
var object = {};
for (let i = 0; i < 10; i++) {
    const index = Math.floor (Math.random () * 10000);
    array[index] = 1;
    object[index] = 1;
    indexes.push (index);
}

Tests:

Array
let sum = 0; for (let i = indexes.length - 1 ; i >= 0 ; i--) { const index = indexes[i]; sum += array[index]; }
Object
let sum = 0; for (let i = indexes.length - 1 ; i >= 0 ; i--) { const index = indexes[i]; sum += object[index]; }

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:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON data and explain what is being tested.

**Benchmark Definition**

The benchmark definition represents two different approaches to access a large but empty array versus a small object in JavaScript. The main difference between the two approaches lies in how they iterate over the indices of the arrays/object.

**Approach 1: Array Access**

```javascript
for (let i = indexes.length - 1 ; i >= 0 ; i--) {
    const index = indexes[i];
    sum += array[index];
}
```

This approach uses a traditional for loop to iterate over the indices of the `array` in reverse order. The `indexes` array is used as a mapping between the original random indices and the new indices in the `array`.

**Approach 2: Object Access**

```javascript
for (let i = indexes.length - 1 ; i >= 0 ; i--) {
    const index = indexes[i];
    sum += object[index];
}
```

This approach is similar to Approach 1, but instead of accessing the `array` using an index, it accesses the `object` directly using the same mapping provided by the `indexes` array.

**Options Compared**

The benchmark compares two options:

1. **Array Access**: Using a traditional for loop to iterate over the indices of the `array`.
2. **Object Access**: Directly accessing the `object` using the `indexes` array as a mapping.

**Pros and Cons**

* **Array Access**
	+ Pros:
		- More predictable behavior, as the iteration order is deterministic.
		- Might be faster due to caching or optimization by JavaScript engines.
	+ Cons:
		- May lead to slower performance in certain scenarios due to overhead of accessing an array.
* **Object Access**
	+ Pros:
		- Can be faster due to direct access and potential caching optimizations.
	+ Cons:
		- Behavior can be less predictable, as the iteration order is not deterministic.

**Other Considerations**

* The use of `indexes` array as a mapping between original indices and new indices in both approaches allows for efficient and consistent access to the data.
* Both approaches assume that the random indices generated are within the bounds of the `array` or `object`.

**Library Usage**

None, this benchmark does not use any external libraries.

**Special JS Features/Syntax**

This benchmark uses the following JavaScript features:

* For loop with a decrementing counter
* Object access using bracket notation (`[]`)
* Variable scope and assignment

These features are part of standard JavaScript syntax and are widely supported across browsers.

**Alternatives**

There are several alternatives to this benchmark, including:

1. **Array iteration using `forEach`**: Instead of using a traditional for loop, you could use the `forEach` method to iterate over the indices of the array.
```javascript
array.forEach((value, index) => {
    // do something with value and index
});
```
2. **Using `map` or `reduce` methods**: If you need to perform a transformation or aggregation on the values in the array, you could use the `map` or `reduce` methods instead of iterating manually.
```javascript
const sum = indexes.reduce((acc, index) => {
    return acc + (array[index] || 0);
}, 0);
```
These alternatives may provide different performance characteristics and are worth considering depending on your specific use case.

Related benchmarks:

Large but empty Array versus Small Object (Access wise) (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

No previous run results

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