Benchmark: array filter vs loop, to remove matching element from array

Script Preparation code:

a = [1,3,56,7,2,44,9,3,44,3];

Tests:

filter
a.filter( item => item !== 3 );
loop
let i = a.length; while( i-- ){ if( a[i] === 3 ) a.splice(i,1); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
filter
loop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:131.0) Gecko/20100101 Firefox/131.0

Browser/OS: Firefox 131 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
filter	4846502.5 Ops/sec
loop	23790740.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):

LLMs can make mistakes. Check important info.

The benchmark tests different approaches to removing elements from an array in JavaScript, specifically comparing the performance of using the `.filter()` method versus a traditional `while` loop combined with `splice()`.

### Test Cases Overview

1. **Filter Method**:
   - **Benchmark Definition**: `a.filter(item => item !== 3);`
   - **Test Name**: "filter"
   - **Description**: This test uses the `Array.prototype.filter()` method. It creates a new array with all elements that pass the test implemented by the provided function. In this case, it filters out any elements that are equal to `3`.

2. **Loop with Splice**:
   - **Benchmark Definition**: 
     ```javascript
     let i = a.length;
     while (i--) {
         if (a[i] === 3) a.splice(i, 1);
     }
     ```
   - **Test Name**: "loop"
   - **Description**: This test involves manually iterating over the array from the end to the beginning, checking each element, and using `splice()` to remove any occurrences of `3`. This approach modifies the original array in place.

### Comparison of Options

- **Performance**:
  - **Loop with Splice**: Achieved a significantly higher execution speed with `23,790,740` executions per second.
  - **Filter Method**: Registered `4,846,502.5` executions per second.
  - **Conclusion**: In this benchmark, the loop with splice is more efficient than the filter method in terms of raw execution speed.

- **Readability and Maintainability**:
  - **Filter Method**: The use of `.filter()` is generally more readable, expressing the intent clearly without needing to manage the loop and conditionals manually. It is more declarative.
  - **Loop with Splice**: This approach can be considered more complex and may be harder to understand at a glance, especially for those unfamiliar with iterating in reverse.

- **Array Mutation**:
  - **Filter Method**: This creates a new array and does not mutate the original array `a`, which could be beneficial in cases where immutability is important.
  - **Loop with Splice**: This modifies the original array, which could lead to unintended side effects if `a` is used later in the code without a copy.

### Other Considerations

- **Memory Usage**: The `.filter()` method could consume more memory since it creates a new array. In contrast, the loop modifies the array in place, potentially reducing memory usage, especially for large arrays.

- **Libraries**: The benchmark does not use any specific libraries. It solely relies on the core JavaScript features and methods available in all JavaScript environments.

- **Browser Compatibility**: Both methods are widely supported across different browsers, making either approach suitable for most web applications.

### Alternative Approaches

Several additional methods could be considered for removing items from an array:

1. **Using For Loop**: Similar to the while loop, a traditional `for` loop can be employed. 
   ```javascript
   for (let i = 0; i < a.length; i++) {
       if (a[i] === 3) a.splice(i--, 1); // Decrement i to account for the removed item
   }
   ```

2. **Using `reduce()`**: You can also use `Array.prototype.reduce()` to build a new array excluding the target element:
   ```javascript
   a.reduce((acc, item) => {
       if (item !== 3) acc.push(item);
       return acc;
   }, []);
   ```

3. **Using `forEach()` with `filter()`**: While not as performant as using either `filter()` or a loop directly, a `forEach()` approach can also be considered. However, it is not recommended for removal as it lacks the functionality of directly modifying the original array.

### Conclusion

Choosing between these methods often depends on the specific use case, including performance requirements, desire for code clarity, and the need to maintain immutability. While the loop with `splice` may have a performance edge in this scenario, the simplicity and ease of understanding of `.filter()` can be advantageous in many situations, particularly where readability is a priority.

Related benchmarks:

array filter vs loop, to remove matching element from array (version: 0)

Comparing performance of: filter vs loop

Created: 2 months ago by: Guest

Jump to the latest result

filter

loop

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):