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: one year 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 one year ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON compares two different methods for removing matching elements from an array in JavaScript: using the `filter` method and a traditional loop with `splice`.

### Test Methods

1. **Using `Array.prototype.filter`:**
   - **Benchmark Definition:** `a.filter(item => item !== 3);`
   - This method creates a new array containing all elements of the original array `a` for which the provided function returns `true`. In this case, it keeps all items that are not equal to `3`.

2. **Using a traditional loop with `splice`:**
   - **Benchmark Definition:** 
   ```javascript
   let i = a.length;
   while(i--) {
       if (a[i] === 3) a.splice(i, 1);
   }
   ```
   - This method iterates over the array in reverse and removes elements that are equal to `3` directly from the original array by using the `splice` method, which modifies the array in place.

### Performance Results

From the latest benchmark results, we can see the performance comparison:
- **Loop (with splice)**: 23,790,740 executions per second
- **Filter**: 4,846,502.5 executions per second

Here, the loop method is significantly faster than the filter method.

### Pros and Cons

#### `Array.prototype.filter`
- **Pros:**
  - Cleaner and more readable code.
  - Functional programming style, offering immutability (creates a new array instead of modifying the original).
- **Cons:**
  - Slower performance, particularly with large arrays, because it must iterate over the entire array and create a new array.
  - Creates a new array in memory, which can lead to increased memory usage if the original array is large.

#### Traditional Loop with `splice`
- **Pros:**
  - Faster execution time, especially with large data sets where performance is critical.
  - Modifies the original array in place, which can be more memory efficient as it doesn't create a new array.
- **Cons:**
  - Code can be less readable and more error-prone, especially if not handled carefully (e.g., potential off-by-one errors).
  - Mutates the original array, which may lead to unintended side effects if other parts of the code rely on the original array’s state.

### Other Considerations

- **Use Cases:** The choice between these two methods depends greatly on the specific use case. If retaining the original array is important and the dataset is relatively small, the `filter` method may be more appropriate despite being slower. Conversely, if performance is critical and the original array does not need to be preserved, the loop approach is preferable.
  
- **Alternatives:** Other alternative methods could include:
  - **Using `reduce`:** This method can also be leveraged to create a new filtered array: `a.reduce((acc, item) => { if (item !== 3) acc.push(item); return acc; }, []);`.
  - **Using `forEach`:** To manually push non-matching items to a new array, but this is less elegant.
  - **Using the `for...of` loop:** Can also be crafted to filter out matching elements.

In conclusion, both methods have their advantages and disadvantages, leading to performance differences that should be considered in the context of the specific application requirements. Understanding how these methods work and their implications is beneficial for making informed decisions while coding in JavaScript.

Related benchmarks:

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

Comparing performance of: filter vs loop

Created: one year ago by: Guest

Jump to the latest result

filter

loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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