Benchmark: JS iterator vs array

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

const items = [1,2,3,4,5,6,7,8,9,10];

Tests:

Array
const arrayTransform = items.filter(i => i % 2 === 0).map(n => n * 2);
Iterator
const iterTransform = items.values().filter(i => i % 2 === 0).map(n => n * 2).toArray();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array
Iterator

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/134.0.0.0 Safari/537.36

Browser/OS: Chrome 134 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array	14774904.0 Ops/sec
Iterator	2600266.2 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON compares two methods of transforming data in JavaScript: using an array versus using an iterator. These methods involve filtering and mapping elements contained in a list of numbers from 1 to 10.

### Options Compared

1. **Array Method:**
   - **Benchmark Definition:** 
     ```javascript
     const arrayTransform = items.filter(i => i % 2 === 0).map(n => n * 2);
     ```
   - **Transformation Steps:**
     - **Filtering:** It filters elements to retain only even numbers.
     - **Mapping:** It then maps those filtered numbers by multiplying them by 2.
  
2. **Iterator Method:**
   - **Benchmark Definition:**
     ```javascript
     const iterTransform = items.values().filter(i => i % 2 === 0).map(n => n * 2).toArray();
     ```
   - **Transformation Steps:**
     - **Iterators:** It begins by retrieving an iterator of the values of `items`.
     - **Filtering & Mapping:** Similar to the array approach, it filters for even numbers and maps them to double their value.
     - **Final Conversion:** The `.toArray()` method indicates an effort to convert the final iterator back into an array.

### Pros and Cons

- **Array Method:**
  - **Pros:**
    - Simplicity: Readable and straightforward notation that is familiar to most JavaScript developers.
    - Directly leveraging the array methods that are highly optimized in most JavaScript engines.
  - **Cons:**
    - Performance: Arrays may incur higher overheads in terms of memory usage, especially with a large dataset.

- **Iterator Method:**
  - **Pros:**
    - Efficiency with large data sets: Iterators can potentially provide more memory-efficient processing, as they do not create intermediate arrays.
    - Flexibility: Allows processing sequences in a more controlled manner without needing to load entire datasets into memory at once.
  - **Cons:**
    - Complexity: More complex to read and understand, especially for developers less familiar with iterators and their usage in JavaScript.
    - Performance: In this benchmark, it performs worse than the array method, indicating it might not be optimal even for its intended use-case.

### Other Considerations

- **JavaScript Features:** The use of the `values()` method highlights how JavaScript provides iterable protocols, allowing developers to traverse through iterable collections like arrays through iterators. However, the effectiveness of this method can differ based on the environment and the specific operations being performed.

- **Performance Metrics:** The benchmark results show that the array approach executed 14,774,904 operations per second, while the iterator approach executed only 2,600,266.25 operations. This stark difference illustrates the potential impact of choosing one method over another in terms of performance.

### Alternatives

- **For Loops:** A traditional `for` loop for filtering and mapping could also be tested. This approach often has the advantage of being easy to optimize and can yield better performance in specific scenarios.

- **Reduce Method:** Another option could use the `reduce` function which both filters and maps in a single pass through the array, possibly improving performance.

- **Libraries:** While the benchmark does not involve external libraries, libraries like Lodash offer utility functions that could be used to achieve similar transformations in a more concise and potentially optimized manner.

Overall, this benchmark serves as an insightful demonstration of how different data handling methods can impact performance and maintainability within JavaScript code, with considerations for context and data size playing crucial roles in decision-making.

Related benchmarks:

JS iterator vs array (version: 1)

Comparing performance of: Array vs Iterator

Created: one month ago by: Guest

Jump to the latest result

Array

Iterator

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):