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 specifically evaluates two different approaches for removing matching elements (specifically the number `3` in this case) from an array in JavaScript. Here’s a breakdown of the tested options, their pros and cons, and other considerations.

### Options Compared

1. **Using `Array.prototype.filter()`**
   - **Test Case:** 
     ```javascript
     a.filter(item => item !== 3);
     ```
   - **Description:** The `filter` method creates a new array with all elements that pass the test implemented by the provided function. In this case, it retains elements that are not equal to `3`.

2. **Using a `while` loop combined with `Array.prototype.splice()`**
   - **Test Case:** 
     ```javascript
     let i = a.length;
     while (i--) {
         if (a[i] === 3) a.splice(i, 1);
     }
     ```
   - **Description:** This approach involves manually iterating through the array from the last element to the first and removing elements (in this case, the number `3`). The `splice` method changes the original array by adding or removing elements.

### Pros and Cons of Each Approach

#### 1. Array.filter()
- **Pros:**
  - **Immutability:** The `filter` method does not modify the original array. Instead, it returns a new array, making it a safer choice in functional programming patterns where immutability is preferred.
  - **Readability:** Code using `filter` is generally more concise and expressive, making it easier to understand at a glance.
  - **Chainable:** Being a method of the Array prototype, `filter` can be chained with other array methods like `map`, `reduce`, etc.

- **Cons:**
  - **Performance:** Creating a new array can introduce additional memory overhead, and in some scenarios where performance is critical and the size of the array is large, this overhead can be significant. The time complexity remains O(n).
  
#### 2. While Loop with Splice
- **Pros:**
  - **In-place Modification:** This approach modifies the original array directly without creating a new one, which can be beneficial for memory usage when dealing with large arrays.
  - **Potentially Faster for Larger Arrays:** Depending on use case and specific array characteristics, especially when removing many matched items, it might offer better performance.

- **Cons:**
  - **Mutability:** This method changes the original array, which can lead to bugs if the original data is needed later in its unaltered state. It may also violate functional programming principles.
  - **Complexity and Readability:** The use of a loop, particularly one that modifies the array while iterating through it (which can lead to errors if not handled correctly), makes the code less elegant and harder to read.
  - **Performance Issues with Splice:** The `splice()` method must re-index the array every time an element is removed, which can be less efficient with larger data sets.

### Benchmark Results
According to the benchmark results obtained with Firefox 131, the loop method (`while` with `splice`) executes at approximately **23,790,740 executions per second**, while the `filter` method runs at about **4,846,502.5 executions per second**. This result strongly suggests that the loop method is significantly faster in this instance, primarily due to the reasons outlined above.

### Other Considerations and Alternatives
- **Other Array Methods:** There are other methods such as `forEach`, `map`, or manually filtering using a `for` loop that could be considered, each having its own performance characteristics.
- **Typed Arrays:** If performance is paramount and the data set is large and uniform in type, using typed arrays might yield better performance results.
- **Functional Libraries:** Libraries like lodash provide utility functions that could handle such tasks with additional performance optimizations or chaining capabilities.

In conclusion, the choice between these two approaches depends on specific needs: whether immutability or raw performance is prioritized, along with considerations regarding code maintainability and readability.

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):