Benchmark: Array loop vs foreach vs map into array

Script Preparation code:

   var arr = [];
    for (var i = 0; i < 1000; i++) {
      arr[i] = i;
    }
  
    function someFn(i) {
      return i * 3 * 8;
    }

Tests:

foreach
let newArray = [] arr.forEach(function (item){ newArray.push(someFn(item)); })
for
let newArray = [] for (var i = 0, len = arr.length; i < len; i++) { newArray.push(someFn(arr[i])); }
map
let newArray = arr.map(item => someFn(item))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for
map

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

I'd be happy to explain what's being tested in the provided benchmark.

**Overview of the Benchmark**

The benchmark measures the performance of three different approaches for executing an array loop:

1.  **Array Loop**: A traditional `for` loop that iterates over the array and performs calculations on each element.
2.  **Foreach Loop**: The `forEach()` method, which is a more modern and concise way to iterate over arrays in JavaScript.
3.  **Map into Array**: The `map()` function, which applies a transformation to each element of an array and returns a new array.

**Options Comparison**

The three options are compared to determine which one performs best in terms of speed. Here's a brief overview of each approach:

*   **Array Loop**: This is the traditional way of iterating over arrays in JavaScript. It involves using a `for` loop with an index variable, which can be slow because it creates a new scope for each iteration.
*   **Foreach Loop (using `forEach()`)**: The `forEach()` method is called on each element of the array, executing the provided callback function once per iteration. This approach is generally faster than traditional loops because it doesn't require explicit index management.
*   **Map into Array (using `map()`)**: The `map()` function applies a transformation to each element of an array and returns a new array. In this benchmark, the transformation involves multiplying each number by 3 and 8 using the `someFn()` function.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

*   **Array Loop**: Pros - traditional syntax, easy to understand; Cons - can be slower due to scope management and potential for array indexing errors.
*   **Foreach Loop (using `forEach()`)**: Pros - concise syntax, faster execution; Cons - may not be suitable for all scenarios where explicit control is required.
*   **Map into Array (using `map()`)**: Pros - concise syntax, fast execution; Cons - requires careful consideration of the transformation function's behavior.

**Library and Special JavaScript Features**

The benchmark uses the following library:

*   None. This benchmark doesn't rely on any external libraries.

However, it does utilize a special JavaScript feature: the arrow function syntax (`=>`).

**Arrow Function Syntax**

Arrow functions are a concise way to define small functions in JavaScript. They have several advantages over traditional `function()` expressions, including:

*   Concise syntax
*   Implied "this" context
*   No explicit return type declaration

In this benchmark, the `map()` function uses an arrow function (`item => someFn(item)`) to transform each element of the array. This syntax is more concise and readable than a traditional function expression.

**Other Alternatives**

If you're interested in exploring other alternatives for iterating over arrays or performing transformations, here are some options:

*   **Using `reduce()`**: The `reduce()` method applies a transformation to an accumulator value and returns a new array. It can be used instead of `map()` when working with arrays that require more complex calculations.
*   **Using a custom loop**: If you need more control over the iteration process or want to avoid using built-in methods like `forEach()` or `map()`, you can use a traditional loop (e.g., `for` loop, `while` loop) to iterate over the array and perform calculations.

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/113.0

Browser/OS: Firefox 113 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
foreach	63922.8 Ops/sec
for	170346.9 Ops/sec
map	96041.2 Ops/sec

Related benchmarks:

Array loop vs foreach vs map into array (version: 0)

Comparing performance of: foreach vs for vs map

Created: one year ago by: Guest

Jump to the latest result

foreach

for

map

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):