Benchmark: forEach vs filtermap

Script Preparation code:

const testArray = [30, 31, 32, 29, 31, 16, 24, 22, 43, 56, 25, 34];
let outpUtArray = [];

Tests:

forEach
const testArray = [30, 31, 32, 29, 31, 16, 24, 22, 43, 56, 25, 34]; let outpUtArray = []; testArray.forEach(element => { if(element <18){ return console.log('Mistake:', element); } else { outpUtArray.push(element * element); } }); console.log(outpUtArray);
filter + map
const testArray = [30, 31, 32, 29, 31, 16, 24, 22, 43, 56, 25, 34]; const mapArray = testArray .filter(element => { return element >= 18; }) .map(element => { return element * element; }); console.log(mapArray);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach
filter + map

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's break down the JavaScript microbenchmark provided by MeasureThat.net.

**Benchmark Definition**
The benchmark defines two test cases: `forEach` and `filter + map`. The purpose of this benchmark is to compare the performance of these two approaches in filtering and mapping an array.

**Script Preparation Code**
Both test cases start with the same script preparation code, which creates a test array containing 12 numbers. The output array is initialized as an empty array.

**Test Cases**

### 1. `forEach`

The first test case uses the `forEach` method to filter and map the array. Here's what happens:

*   The `forEach` method iterates over each element in the `testArray`.
*   For each element, it checks if the element is less than 18 using an `if` statement.
*   If the condition is true, it returns a log message with the value of `element` to the console. However, since `forEach` does not return its iterator directly and instead logs to the console inside the callback function, this test case seems to have some unnecessary logging at the end which might skew results.
*   If the condition is false (i.e., `element >= 18`), it pushes the square of `element` (`element * element`) into the `outputArray`.

### 2. `filter + map`

The second test case uses a combination of `filter` and `map` methods to achieve the same result as the first test case:

*   The `filter` method creates a new array with elements that pass the condition (i.e., `element >= 18`).
*   The resulting array is then piped into the `map` method, which squares each element in the filtered array.
*   The final output is logged to the console.

**Library Usage**

There are no libraries used explicitly in these test cases. However, some built-in JavaScript functions and methods are utilized, such as `forEach`, `filter`, `map`, and `console.log`.

**Special JS Feature/Syntax**

None of the provided test cases make use of any special JavaScript features or syntax that would skew the results.

**Pros and Cons of Different Approaches**

*   **`forEach`**: Pros:
    *   Simplistic approach for filtering and mapping.
    *   Often considered more concise than using `filter` and `map`.
*   **`filter + map`**: Pros:
    *   More explicit and readable.
    *   Allows for better control over the filtering process.

Cons of each:

*   **`forEach`**:
    *   Potential performance overhead due to logging inside the callback function.
    *   Does not allow direct access to the array elements, which might be a disadvantage in some cases.
*   **`filter + map`**:
    *   May require more lines of code than using `forEach`.
    *   Can lead to less concise code if the filtering logic becomes complex.

Other Alternatives

For similar use cases, other methods like `reduce()` can also be considered for mapping and filtering purposes. However, their performance may vary depending on the specific implementation and requirements.

Here's a brief example of how you might implement this using `reduce()`:
```javascript
const testArray = [30, 31, 32, 29, 31, 16, 24, 22, 43, 56, 25, 34];

const outputArrayUsingReduce = testArray.reduce((acc, current) => {
    if (current >= 18) {
        return [...acc, current * current];
    } else {
        return acc;
    }
}, []);

console.log(outputArrayUsingReduce);
```
Keep in mind that performance characteristics of `reduce()` can vary significantly based on its parameters and the implementation specifics.

Related benchmarks:

forEach vs filtermap (version: 0)

Comparing performance of: forEach vs filter + map

Created: 6 years ago by: Guest

Jump to the latest result

forEach

filter + map

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):