Benchmark: flat vs forEach - MeasureThat.net

HTML Preparation code:

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

Script Preparation code:

const createNestedArray = (depth, width) => {
  let arr = [];
  for (let i = 0; i < width; i++) {
    arr.push(Array.from({ length: depth }, (_, j) => j));
  }
  return arr;
};

const depth = 1000;
const width = 100;
const nestedArray = createNestedArray(depth, width);

Tests:

flat()
nestedArray.flat();
forEach()
const flattened = []; nestedArray.forEach(subArray => { flattened.push(...subArray); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
flat()
forEach()

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 11 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
flat()	416.0 Ops/sec
forEach()	808.8 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 11 days ago):

LLMs can make mistakes. Check important info.

The benchmark defined as "flat vs forEach" aims to compare the performance of two different approaches for flattening a nested array in JavaScript: using the `Array.prototype.flat()` method and a traditional `forEach` loop with the spread operator.

### Options Compared
1. **flat() Method**:
   - **Definition**: `nestedArray.flat()` is a built-in array method that flattens nested arrays to a specified depth. In this case, it would flatten a 2D array (the nested array) into a 1D array.
   - **Pros**:
     - Simplicity: It is a concise and straightforward method for flattening arrays.
     - Readability: The intent of flattening is clear, making the code easier to understand at a glance.
     - Performance: Optimized in modern JavaScript engines, which may lead to faster execution in many scenarios.
   - **Cons**:
     - Flexibility: Offers less control compared to custom implementations; for example, it has built-in depth that might not cater to all specific requirements.

2. **forEach() Approach**:
   - **Definition**: `nestedArray.forEach(subArray => { flattened.push(...subArray); })` uses the `forEach` loop to iterate over each sub-array and the spread operator (`...`) to push each element of the sub-array into the `flattened` array.
   - **Pros**:
     - Flexibility: This method allows for custom processing of the elements as they are flattened, making it adaptable to various needs.
     - Control: You can add additional logic inside the `forEach` loop to handle edge cases or perform extra transformations on the data.
   - **Cons**:
     - Verbosity: The code is longer and less readable compared to using `flat()`.
     - Performance: Depending on the JavaScript engine, it may be slower than the `flat()` method due to multiple calls to `push()` and the spread operator's overhead.

### Benchmark Results Analysis
- The benchmark results indicate that the `forEach()` approach executed 808.78 times per second, while the `flat()` method executed 416.05 times per second in the same environment (Chrome 131 on macOS 10.15.7). This suggests that, in this specific test case, the `forEach()` method outperforms the `flat()` method in terms of execution speed.

### Considerations
- **Use Case**: The choice between these two methods may depend on specific use cases. If you have simple nested arrays and prioritize readability and concise code, using `flat()` is appropriate. However, if you need more flexibility, such as handling more complex nested structures or applying custom transformations, the `forEach()` method may be better.
- **Browser Compatibility**: `Array.prototype.flat()` is supported in modern browsers but might not be available in older versions or certain environments. It's important to check compatibility if cross-browser use is a concern.

### Alternatives
1. **Reduce Method**: Another common way to flatten arrays is to use the `reduce` method. The implementation would be like:
   ```javascript
   const flattened = nestedArray.reduce((acc, subArray) => acc.concat(subArray), []);
   ```
   - **Pros**: This method is readable and provides control over the flattening process.
   - **Cons**: It may not perform as well as `flat()` in certain JavaScript engines.

2. **Recursion**: Flattening with recursion can handle arbitrary depth.
   ```javascript
   const flattenDeep = arr => {
     return arr.reduce((acc, val) => acc.concat(Array.isArray(val) ? flattenDeep(val) : val), []);
   };
   ```

3. **Array.prototype.concat():** Similar to `reduce`, this method can be used but is less common for flattening nested arrays compared to more optimized approaches like `flat()`.

In summary, while both methods are effective for flattening nested arrays, their differences lie in simplicity, performance, and flexibility. The choice of method should be guided by the specific requirements of the use case at hand, available browser compatibility, and the target performance characteristics.

Related benchmarks:

flat vs forEach (version: 1)

Comparing performance of: flat() vs forEach()

Created: 11 days ago by: Guest

Jump to the latest result

flat()

forEach()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 11 days ago):