Benchmark: .map vs .forEach

Script Preparation code:

var array = [];
array.forEach(i => array.push(i));

var someFunction = num => num * 2 * 3;

Tests:

.map
const arr1 = array.map(i => someFunction(i));
.forEach
const arr2 = []; array.forEach(i => { arr2.push(someFunction(i)); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
.map
.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 provided JSON and explain what's being tested.

**Benchmark Definition**

The benchmark measures the performance difference between using the `Array.prototype.map()` method versus the `Array.prototype.forEach()` method to perform a simple calculation on an array of numbers.

**Script Preparation Code**

The script preparation code initializes an empty array `array` and defines a function `someFunction` that takes a number as input, multiplies it by 2 and then by 3, and returns the result.

**Html Preparation Code**

There is no HTML preparation code provided, which means that this benchmark focuses solely on JavaScript performance comparisons.

**Individual Test Cases**

The test cases consist of two scenarios:

1. **`.map()`**: This scenario tests how long it takes to apply the `someFunction` calculation to each element in an array using the `.map()` method.
2. **`.forEach()`**: This scenario tests how long it takes to apply the same `someFunction` calculation to each element in an array using the `.forEach()` method.

**Library and Special JS Feature**

Neither of these test cases uses any libraries or special JavaScript features that are not part of the standard language specification. The focus is solely on comparing the performance of two built-in methods: `.map()` and `.forEach()`.

**Comparison of Approaches**

Now, let's discuss the pros and cons of each approach:

* **`.map()`**: This method creates a new array with the results of applying the provided function to each element in the original array. It is generally faster than `.forEach()` because it avoids the overhead of updating the original array.
	+ Pros: More memory-efficient, potentially faster execution time.
	+ Cons: Creates a new array, can be less intuitive for simple use cases where you only need to perform an action on each element.
* **`.forEach()`**: This method does not create a new array; it simply executes the provided function for each element in the original array. It is generally slower than `.map()` because it updates the original array.
	+ Pros: Does not consume additional memory, can be more intuitive for simple use cases where you only need to perform an action on each element.
	+ Cons: Updates the original array, potentially slower execution time due to the overhead of updating the array.

**Other Alternatives**

If you were to compare `.map()` and `.forEach()` with other methods or libraries, here are some alternatives:

* **`Array.prototype.reduce()`**: This method reduces the array to a single value by applying a function to each element. It can be faster than `.map()` for simple use cases where you need to calculate a sum or product.
* **`Array.prototype.filter()`**: This method creates a new array with only the elements that pass the provided test function. Like `.map()`, it is generally faster than `.forEach()` but consumes more memory.

In summary, this benchmark provides a useful comparison between two fundamental JavaScript methods: `.map()` and `.forEach()`. Understanding the pros and cons of each approach can help developers optimize their code for better performance.

Related benchmarks:

.map vs .forEach (version: 0)

Comparing performance of: .map vs .forEach

Created: 6 years ago by: Guest

Jump to the latest result

.map

.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):