Benchmark: Array.reduce vs for loop vs Array.forEach vs decrement while

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 accum = 0;
	for(var intCtr=0; intCtr<pArray.length; intCtr++) {
		accum += pArray[intCtr];
	}
	return accum;
}
function decrWhile(pArray) {
	var accum = 0;
  	var index = pArray.length;
	while(index--) {
		accum += pArray[index];
	}
	return accum;
}
function doForEach(pArray) {
	var accum = 0;
	pArray.forEach(function(item) {
		accum += item;
	});
}

Tests:

reduce
var redeuceResult=0; redeuceResult = doRedeuce(arrRandom);
for loop
var loopResult=0; loopResult = doLoop(arrRandom);
forEach
var forEachResult=0 forEachResult = decrWhile(arrRandom)
decrement while
var decrWhileResult=0; decrWhileResult = doForEach(arrRandom)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce
for loop
forEach
decrement while

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:141.0) Gecko/20100101 Firefox/141.0

Browser/OS: Firefox 141 on Windows

View result in a separate tab

Test name	Executions per second
reduce	1077420.4 Ops/sec
for loop	2392480.2 Ops/sec
forEach	1862912.9 Ops/sec
decrement while	488600.0 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 is being tested.

**Benchmark Overview**

The test measures the performance of four different approaches to summing 1000 random numbers:

1. `Array.reduce()`
2. For loop
3. `Array.forEach()` (with a custom decrementing index)
4. Custom "decrement while" loop

**Approach 1: `Array.reduce()`**

`Array.reduce()` is a built-in JavaScript function that reduces an array to a single value by applying a callback function to each element in the array. In this case, the callback function simply adds the current number to the accumulator.

Pros:

* Concise and readable code
* Built-in functionality makes it easy to understand and implement

Cons:

* May have performance overhead due to the need to create an iterator object and iterate over the array
* Can be slower than a custom loop for large arrays

**Approach 2: For Loop**

A traditional for loop iterates over the elements of an array, executing a block of code for each element.

Pros:

* Fast execution speed, as it doesn't require creating an iterator object or iterating over the array
* Control over iteration order and index access

Cons:

* Can be verbose and less readable than other approaches
* May not be suitable for large arrays due to stack size limitations

**Approach 3: `Array.forEach()`**

`Array.forEach()` is another built-in JavaScript function that executes a callback function for each element in an array. In this case, the callback function adds the current number to the accumulator.

Pros:

* Similar to `Array.reduce()`, but with a more concise syntax
* Can be faster than `Array.reduce()` due to optimized iterator implementation

Cons:

* May have performance overhead due to the need to create an iterator object and iterate over the array
* Custom decrementing index is not supported by default

**Approach 4: Custom "Decrement While" Loop**

This custom loop uses a decrementing index to access elements in the array, similar to a traditional for loop.

Pros:

* Fast execution speed, as it doesn't require creating an iterator object or iterating over the array
* Control over iteration order and index access

Cons:

* May be less readable than other approaches due to the custom logic
* Not supported by default in JavaScript, requiring manual implementation

**Library Used**

None explicitly mentioned, but `Math.random()` is used to generate random numbers.

**Special JS Features/Syntax**

None explicitly mentioned.

**Alternative Approaches**

Other approaches that could be tested include:

* Using `Array.prototype.map()` with a callback function
* Using `Array.prototype.every()` or `Array.prototype.some()` with a callback function
* Using Web Workers for parallel computation

Note that these alternatives may not provide significant performance improvements over the existing approaches and would require additional benchmarking to confirm.

Related benchmarks:

Array.reduce vs for loop vs Array.forEach vs decrement while (version: 0)

A test summing 1000 random numbers, 1 - 10000

Comparing performance of: reduce vs for loop vs forEach vs decrement while

Created: 7 years ago by: Guest

Jump to the latest result

reduce

for loop

forEach

decrement while

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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