Benchmark: filter.foreach vs foreach with condition

Script Preparation code:

var arr = [];
for (var i = 0; i < 12345; i++) {
    arr[i] = i;
}

var sumForEach = 0,
    sumFilter = 0;

Tests:

forEach
arr.forEach((item) =>{if(item%2 == 0){ sumForEach++; }});
filter
arr.filter((item) => item%2 == 0).forEach((item) => { sumFilter++; });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach
filter

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/130.0.6723.90 Mobile/15E148 Safari/604.1

Browser/OS: Chrome Mobile iOS 130 on iOS 18.0

View result in a separate tab

Test name	Executions per second
forEach	1626.6 Ops/sec
filter	1443.3 Ops/sec

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

LLMs can make mistakes. Check important info.

The benchmark testing provided compares two different approaches for iterating over an array and counting even numbers: using `Array.prototype.forEach()` with a condition versus using `Array.prototype.filter()` followed by `forEach()`.

### Descriptions of the Tests:

1. **Test Using `forEach`:**
   - **Benchmark Definition:** 
     ```javascript
     arr.forEach((item) => { if (item % 2 == 0) { sumForEach++; } });
     ```
   - **Test Name:** "forEach"
   - **Description:** This test uses the `forEach` method to iterate through each item in the `arr` array. For each item, it checks if the item is even (i.e., `item % 2 == 0`). If the condition is satisfied, it increments a counter (`sumForEach`) for each even number found.

2. **Test Using `filter`:**
   - **Benchmark Definition:** 
     ```javascript
     arr.filter((item) => item % 2 == 0).forEach((item) => { sumFilter++; });
     ```
   - **Test Name:** "filter"
   - **Description:** In this approach, the test first uses the `filter` method to create a new array containing only the even numbers. Subsequently, the `forEach` method is used on the resulting array to count the even numbers by incrementing a separate counter (`sumFilter`).

### Comparison of Approaches:

**Pros and Cons:**

- **forEach:**
  - **Pros:** 
    - More straightforward in terms of readability and intent. You execute a single pass over the array, making it efficient for large datasets.
    - Requires less memory since there's no need to create an intermediate array.
  - **Cons:** 
    - Involves more manual checks. If additional processing or transformations were needed for the even numbers, the code could become more complicated.

- **filter followed by forEach:**
  - **Pros:** 
    - This method is arguably cleaner for some developers as it separates the concerns of filtering and processing. You get a clear picture of what's happening step-by-step.
    - Can be easier to extend; if you want further manipulation of filtered items, the intermediate array created by `filter` is there to use.
  - **Cons:** 
    - This creates an unnecessary intermediate array, potentially leading to higher memory usage and possibly slower performance, especially for large datasets.
    - Requires two passes over the array, which can lead to performance degradation compared to the single pass in the `forEach` method.

### Benchmark Results:

From the benchmark results provided, we see that:
- The `forEach` method has a higher performance, executing approximately **1626** operations per second.
- The `filter` method has a lower performance rate of about **1443** operations per second.

### Other Considerations:

1. **Performance Context:** The difference in execution speed can vary depending on the data size and the environment in which the code is running (e.g., mobile vs. desktop, various JavaScript engines).
2. **Readability vs. Performance:** While performance is an essential consideration, choosing the right approach can depend on the context of the task—readability may take precedence in more complex business logic where maintainability is critical.
3. **Functionality:** If you need to keep the even numbers for further processing beyond counting, `filter` would be beneficial despite its performance hit due to its ability to create an easily manageable subset of data.
4. **Alternative Methods:** Other array methods include `reduce` for customized iterations with complex conditions or `for-of` for ES6-style looping, which can be more performance-efficient for trivial conditions.

In conclusion, the choice between `forEach` with a conditional check versus using `filter` followed by `forEach` boils down to factors such as performance requirements, code readability, and the specific use case of the data being processed. Each method has its own merits, and understanding when to use which technique is an essential skill for developers.

Related benchmarks:

filter.foreach vs foreach with condition (version: 1)

Comparing performance of: forEach vs filter

Created: one month ago by: Guest

Jump to the latest result

forEach

filter

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):