Benchmark: forEach vs reduce vs map vs filter vs for V2

Script Preparation code:

var arr = [];
for (var i = 0; i < 123; i++) {
  arr[i] = i;
}

function someFn(i) {
  return (i * 3 * 8 / 1200 * 0.002 / 40 * 0.2);
}

var sumForEach = 0,
  sumReduce = 0,
  sumMap = 0,
  sumFilter = 0,
  sumFor = 0;

Tests:

forEach
arr.forEach(item => sumForEach += someFn(item));
reduce
sumReduce = arr.reduce((lastValue, item) => { return sumReduce += someFn(item); });
map
arr.map(item => (sumMap += someFn(item)));
filter
arr.filter(item => (sumFilter += someFn(item)));
for
for (var j = 0; j < arr.length; j++) { sumFor += arr[j]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach
reduce
map
filter
for

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

The provided JSON represents a JavaScript microbenchmark test case on the MeasureThat.net website. The benchmark tests four different array iteration methods: `forEach`, `reduce`, `map`, and `for` (with version 2, denoted as V2).

Here's an explanation of each approach:

1. **`forEach`**:
	* This method iterates over the elements of an array using a callback function.
	* In this test case, the `forEach` method is used to iterate over the `arr` array and accumulate the results in the `sumForEach` variable.
	* Pros: Simple to implement, allows for easy iteration over arrays.
	* Cons: Can be slower than other methods due to the overhead of function calls and potential string interning.
2. **`reduce`**:
	* This method applies a binary function (reducer) to each element of an array, accumulating a single value.
	* In this test case, the `reduce` method is used to iterate over the `arr` array and accumulate the results in the `sumReduce` variable.
	* Pros: Efficient for reducing arrays to a single value, avoids unnecessary iterations.
	* Cons: Can be more complex to implement, may have higher memory requirements due to the accumulator.
3. **`map`**:
	* This method creates a new array with the results of applying a provided function to each element in the original array.
	* In this test case, the `map` method is used to iterate over the `arr` array and accumulate the results in the `sumMap` variable.
	* Pros: Returns a new array, allows for transformation of data without modifying the original array.
	* Cons: Can be slower than other methods due to the overhead of creating a new array, potential memory allocation issues.
4. **`for` (V2)**:
	* This method uses a traditional `for` loop with a specified number of iterations to iterate over an array.
	* In this test case, the `for` V2 method is used to iterate over the `arr` array and accumulate the results in the `sumFor` variable.
	* Pros: Can be faster than other methods due to the lack of function call overhead, more predictable performance.
	* Cons: Requires manual iteration and indexing, can be less flexible than other methods.

The test case uses the `someFn` function, which is a custom function that performs some arithmetic calculation. The purpose of this function is not explicitly stated in the benchmark definition, but it appears to be used solely for testing purposes.

Regarding special JavaScript features or syntax:

* There is no explicit mention of any special features or syntax being used in this test case.
* However, it's worth noting that the use of `var` with `i` and `j` variables might raise issues with modern JavaScript versions due to its behavior regarding variable scope and hoisting.

Alternative approaches:

* **Native arrays**: Instead of using `Array.prototype.forEach`, `Array.prototype.reduce`, or `Array.prototype.map`, one could use native array methods like `for...of`, `reduce()`, or `map()` directly on the `arr` array.
* **Other iteration methods**: There are other iteration methods available in JavaScript, such as `every()`, `some()`, and `find()`, which might be used in different scenarios.

It's essential to note that performance differences between these methods can vary depending on the specific use case, browser version, and hardware. The MeasureThat.net website aims to provide a fair representation of performance comparisons, but it's always recommended to consider additional factors when making decisions about iteration methods in your own codebase.

Related benchmarks:

forEach vs reduce vs map vs filter vs for V2 (version: 0)

Comparing performance of: forEach vs reduce vs map vs filter vs for

Created: 5 years ago by: Registered User

Jump to the latest result

forEach

reduce

map

filter

for

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):