Benchmark: Array creation with Array.reduce vs for loop vs Array.forEach(2)

Script Preparation code:

// Create an array of 1000 random intergers between 1 and 10000
var arrRandom = [];
for(var intCtr=0; intCtr<1000; intCtr++) {
  arrRandom.push(Math.floor(Math.random() * Math.floor(10000)));
}

function reduceCallback(accum, curr) {
	return [
      ...accum,
      curr
     ];
}

function doRedeuce(pArray) {
	return pArray.reduce(reduceCallback, []);
}
function doLoop(pArray) {
	var newArray = [];
	for(var intCtr=0; intCtr<pArray.length; intCtr++) {
      newArray.push(pArray[intCtr]);
	}
	return newArray;
}
function doForEach(pArray) {
	var newArray = [];
	pArray.forEach(function(item) {
      newArray.push(pArray[item]);
	});
  	return newArray
}

Tests:

reduce
var redeuceResult = doRedeuce(arrRandom);
for loop
var loopResult = doLoop(arrRandom);
forEach
var forEachResult = doForEach(arrRandom)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce
for loop
forEach

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 is being tested, compared options, their pros and cons, and other considerations.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark test case, specifically measuring the performance of three different methods for creating an array: `Array.reduce`, `for loop`, and `Array.forEach`. The test pushes 1000 random numbers between 1 and 10,000 into an array.

**Comparison Methods**

### 1. Array.prototype.reduce()

The `reduce()` method applies a callback function to each element in the array, accumulating a result. In this case, the callback function simply concatenates the current value to the accumulated array.

Pros:

* Concise and elegant syntax
* Can be used for more complex transformations

Cons:

* May incur additional overhead due to the callback function invocation
* Can lead to stack overflow errors if not implemented carefully

### 2. For Loop

The `for` loop iterates over the array elements, pushing each value into a new array.

Pros:

* Well-known and widely supported syntax
* Easy to implement and debug

Cons:

* Can be slower than other methods due to the overhead of explicit iteration
* May lead to memory allocation issues if not managed carefully

### 3. Array.prototype.forEach()

The `forEach()` method invokes a callback function for each element in the array, but unlike `reduce()`, it does not accumulate any result.

Pros:

* Similar syntax to `for` loop, making it easy to implement
* Avoids stack overflow risks

Cons:

* Does not accumulate the results like `reduce()` does
* May lead to performance issues due to unnecessary callback invocations

**Library Used**

The test case uses the built-in `Array.prototype.reduce()`, `Array.prototype.forEach()`, and standard JavaScript functions (e.g., `Math.floor()`) without any external libraries.

**Special JS Features/Syntax**

None are explicitly mentioned in this benchmark. However, it's worth noting that the use of `let` and `const` variables is implied, although not shown in the provided code snippets.

**Other Considerations**

* The test case pushes 1000 random numbers into an array, which can lead to memory allocation issues if not managed carefully.
* The performance difference between these methods may depend on the specific use case and environment.
* The benchmark only measures the execution time of each method, but does not consider factors like memory usage or garbage collection.

**Alternatives**

Other alternatives for creating arrays could include:

* Using `Array.from()` to create an array from an iterable
* Utilizing libraries like Lodash's `map` function
* Implementing a custom iteration mechanism using iterators and generators

Keep in mind that the choice of method depends on the specific requirements and constraints of your project.

Related benchmarks:

Array creation with Array.reduce vs for loop vs Array.forEach(2) (version: 0)

A test pushing 1000 random numbers, 1 - 10000

Comparing performance of: reduce vs for loop vs forEach

Created: 7 years ago by: Guest

Jump to the latest result

reduce

for loop

forEach

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):