Benchmark: Array fills - MeasureThat.net

Tests:

Array.from
Array.from({ length: 1000 }, () => Array(1000).fill(false));
Array.fills
Array(1000).fill(null).map(() => new Array(1000).fill(false));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.from
Array.fills

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

The provided benchmark focuses on measuring the performance of different methods for creating and filling arrays in JavaScript. Specifically, it compares two distinct approaches to generate a two-dimensional array filled with boolean values (in this case, `false`).

### Test Cases Overview

1. **Array.from Method**  
   **Benchmark Definition**: `Array.from({ length: 1000 }, () => Array(1000).fill(false));`  
   **Test Name**: "Array.from"  
   This method utilizes the `Array.from()` function to create a new array with a specified length of 1000. Each element of this new array is generated by calling a function that returns an array filled with `false` values. The outer array will, therefore, contain 1000 arrays, each of length 1000, filled with `false`.

2. **Array.fill and Array.map Method**  
   **Benchmark Definition**: `Array(1000).fill(null).map(() => new Array(1000).fill(false));`  
   **Test Name**: "Array.fills"  
   In this approach, `Array(1000).fill(null)` creates an array of length 1000 and fills it with `null`. Then, the `map()` function is used to transform each `null` element into a new array of length 1000 filled with `false`. Here, the outer array again ends up with 1000 inner arrays filled with `false`.

### Comparison of Options

**Array.from**  
- **Pros**:  
  - More concise and potentially clearer in terms of intent, as it directly expresses the goal of creating an array from an iterable (in this case, an object with a `length` property).
  - Likely to be faster in some JavaScript engines because it avoids the overhead of creating intermediate structures (like null elements).
  
- **Cons**:  
  - Slightly less flexible since it is always required to use a mapping function to generate the filled array, which may not be preferable in certain contexts.

**Array.fill and Array.map**  
- **Pros**:  
  - The use of `map()` can be more flexible if transformations are required when initializing each element; it provides an opportunity to customize the creation of the inner array elements.
  
- **Cons**:  
  - This method tends to be less efficient due to the creation of intermediate arrays. The initial array is filled with `null`, which introduces overhead, and then a new array is created within the `map()` function, potentially leading to higher memory usage and slower performance.

### Benchmark Result Insights

The results show that the **"Array.fills"** method had a higher number of executions per second (418.4) compared to **"Array.from"** (405.1) in the given test environment. This may suggest that in this specific context, the `Array.fill()` and `map()` combination performed better, possibly due to the optimizations in the JavaScript engine running these benchmarks.

### Additional Considerations and Alternatives

1. **Performance Variation**: Performance can vary based on the JavaScript engine (V8 for Chrome, SpiderMonkey for Firefox, etc.) and the environment (hardware, memory, etc.). Always consider cross-browser compatibility.
  
2. **Memory Usage**: The memory implications of each approach can differ, particularly in larger datasets. Monitoring memory impact may be essential if going beyond simple benchmarks.

3. **Other Alternatives**:  
   - A more efficient approach might include using nested loops for filling arrays, especially when implementing specific initialization logic.
   - Third-party libraries like Lodash or Immutable.js also offer array manipulation techniques, but they come with their overhead and may not provide performance benefits for simple operations.

4. **Code Readability**: While performance is crucial, maintainability of the code should also be considered. Code that is easier to understand and reason about is often preferable, especially in collaborative environments.

By understanding these combinations and their implications, engineers can make informed decisions based on the specific use case requirements, whether they prioritize performance, readability, or flexibility.

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/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array.from	405.1 Ops/sec
Array.fills	418.4 Ops/sec

Related benchmarks:

Array fills (version: 0)

Comparing performance of: Array.from vs Array.fills

Created: one month ago by: Guest

Jump to the latest result

Array.from

Array.fills

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):