Benchmark: Array loop vs foreach vs map populate array with prealloc

Script Preparation code:

var arr = [];
for (var i = 0; i < 1000; i++) {
    arr[i] = i;
}

var arr2 = [];

Tests:

foreach
arr2 = new Array(arr.length); var j = 0; arr.forEach(function (item){ arr2[j] = arr[j]; ++j; })
for
arr2 = new Array(arr.length); for (var i = 0, len = arr.length; i < len; i++) { arr2[i] = arr[i]; }
map
arr2 = arr.map(item => 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

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 benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares three approaches to populate an array with values:

1. `Array` constructor with explicit loop (`for` loop)
2. `forEach` method
3. `map` function

Each approach is used to create a new array (`arr2`) that has the same length as the original array (`arr`). The benchmark aims to measure which approach is fastest.

**Options Compared**

The three approaches are compared in terms of their execution speed, measured by the number of executions per second. This allows us to determine which approach is faster and more efficient for this specific task.

**Pros and Cons of Each Approach**

1. **Array constructor with explicit loop (`for` loop)**:
	* Pros: Can be optimized by the JavaScript engine, as it's a simple iterative operation.
	* Cons: Requires manual looping, which can lead to errors if not done correctly.
2. **forEach** method:
	* Pros: High-level abstraction, easy to read and write, and often optimized by the JavaScript engine.
	* Cons: May incur overhead due to the iteration logic being executed on each call, rather than precompiled and cached.
3. **map** function:
	* Pros: Also high-level abstraction, easy to read and write, and often optimized by the JavaScript engine.
	* Cons: May have additional overhead due to the transformation of each element in the array.

**Library Used**

None explicitly mentioned, but `forEach` method is a built-in JavaScript method that relies on the `length` property of arrays.

**Special JS Feature or Syntax**

The benchmark uses standard JavaScript features and syntax, without any specific experimental features like async/await, generators, or WebAssembly. If it did use one of these features, it would be mentioned in the benchmark definition.

**Other Alternatives**

To perform similar benchmarks, you could consider using other programming languages or libraries that provide similar high-level abstractions for array manipulation, such as:

* Python's `map` function
* Java 8's `Stream` API
* C#'s LINQ

Keep in mind that the specific performance characteristics may vary depending on the language and framework being used.

Related benchmarks:

Array loop vs foreach vs map populate array with prealloc (version: 0)

Comparing performance of: foreach vs for vs map

Created: 5 years ago by: Guest

Jump to the latest result

foreach

for

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):