Benchmark: Array loop: foreach vs map

Script Preparation code:

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

Tests:

foreach
arr.forEach(item => someFn(item))
map
arr.map(item => someFn(item))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
map

Fastest: N/A

Slowest: N/A

Latest run results:

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

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

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark that compares two approaches to iterate over an array: `forEach` and `map`. The benchmark is designed to measure which approach is faster on a specific setup.

**Script Preparation Code**

The script preparation code creates an empty array `arr` with 1000 elements, and then defines a function `someFn` that takes an integer as input and returns the result of multiplying it by 3 and 8 (`i * 3 * 8`).

**Html Preparation Code**

There is no HTML preparation code provided, which means that only the JavaScript code will be executed.

**Benchmark Definitions**

The benchmark has two test cases:

1. `foreach`: This test case uses the `forEach` method to iterate over the array and applies the `someFn` function to each element.
2. `map`: This test case uses the `map` method to create a new array with the result of applying the `someFn` function to each element.

**Comparison**

The benchmark compares the performance of these two approaches on the same JavaScript engine ( Chrome 109) on a Mac OS X 10.15.7 desktop platform. The test measures the number of executions per second for each approach.

**Pros and Cons of Different Approaches:**

* `forEach`:
	+ Pros: More concise and expressive, as it directly iterates over the array elements.
	+ Cons: May have performance overhead due to the iteration process, especially if the array is large.
* `map`:
	+ Pros: Returns a new array with transformed values, which can be useful for certain use cases. Also, modern JavaScript engines are optimized for `map`.
	+ Cons: Creates a new array, which may consume memory and have performance implications.

**Other Considerations**

When working with arrays in JavaScript, it's essential to consider the following:

* Iterating over large arrays using methods like `forEach` or `reduce` can be expensive.
* Creating new arrays using methods like `map`, `filter`, or `slice` can consume memory and have performance implications.

**Library Usage**

There is no explicit library usage mentioned in the benchmark code. However, it's worth noting that some libraries like Lodash or Ramda provide optimized implementations of array methods like `forEach` and `map`.

**Special JS Features or Syntax**

The benchmark uses a simple function definition (`function someFn(i) { ... }`) which is a standard JavaScript syntax. There are no special features or syntaxes used in this example.

**Alternatives**

Other alternatives for iterating over arrays include:

* `for...of` loop: A more modern and expressive way to iterate over arrays.
* `reduce()` method: A way to accumulate values by applying a callback function to each element of the array.
* Manual iteration using indices (`arr[i] = ...; i++`): A low-level approach that requires manual management of indices.

In summary, this benchmark compares the performance of two approaches to iterate over an array: `forEach` and `map`. While both methods have their pros and cons, modern JavaScript engines are optimized for `map`, making it a more efficient choice for many use cases.

Related benchmarks:

Array loop: foreach vs map (version: 0)

foreach vs map

Comparing performance of: foreach vs map

Created: 4 years ago by: Guest

Jump to the latest result

foreach

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):