Benchmark: forEach vs for loop

Tests:

forEach
const a = [1,2,3,4,5,6,7,8,9,10] const b = [] a.forEach(item => { b.push(item) })
for loop
const a = [1,2,3,4,5,6,7,8,9,10] const b = [] for (let i=0;i<a.length;i++) { b.push(a[i]) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach
for loop

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:120.0) Gecko/20100101 Firefox/120.0

Browser/OS: Firefox 120 on Windows

View result in a separate tab

Test name	Executions per second
forEach	9856052.0 Ops/sec
for loop	9241291.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark is comparing two approaches: `forEach` and `for loop`. The script preparation code is empty, which means that no custom JavaScript functions or variables are defined in this test case.

**Options Compared**

There are only two options being compared:

1. `forEach`
2. `for loop`

These two approaches are used to iterate over an array of numbers (`a`) and push each element into a new array (`b`).

**Pros and Cons of Each Approach**

*   **`forEach`**
    *   Pros:
        *   Easier to read and write, as it focuses on the iteration logic.
        *   Less prone to off-by-one errors or array indexing issues.
    *   Cons:
        *   Can be slower due to its synchronous nature and overhead from callback functions.

*   **`for loop`**
    *   Pros:
        *   Faster and more efficient, as it avoids the overhead of callback functions.
        *   More control over iteration logic and potential for better performance in certain scenarios.
    *   Cons:
        *   Can be harder to read and write, especially for those unfamiliar with traditional `for` loops.

**Library Usage**

There is no explicit library usage mentioned in this benchmark. However, it's worth noting that the `forEach` method is a built-in JavaScript function that utilizes the `Array.prototype.forEach()` implementation under the hood.

**Special JS Features or Syntax**

None of the code snippets utilize any special JavaScript features or syntax beyond what's commonly used for basic array operations. This makes them accessible to a wide range of software engineers, regardless of their familiarity with advanced JavaScript concepts.

**Other Alternatives**

Other approaches that could be compared in this benchmark include:

*   **`map()`**: While similar to `forEach`, `map()` returns a new array instead of modifying the original one.
*   **`reduce()`**: This method reduces the array to a single value, making it less suitable for push-to-array scenarios like this benchmark.

To extend this comparison and make it more comprehensive, you could also include other iteration methods like:

*   **`filter()`**: Removes elements from the array based on a condition.
*   **`every()`** and **`some()`**: Test conditions that check every element in an array or some number of elements, respectively.

By considering these additional options, the benchmark can provide a more complete understanding of various iteration techniques in JavaScript.

Related benchmarks:

forEach vs for loop (version: 0)

Comparing performance of: forEach vs for loop

Created: 8 years ago by: Guest

Jump to the latest result

forEach

for loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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