Benchmark: ForEach vs Map for creating new array with concat

Script Preparation code:

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

Tests:

ForEach
let result = []; arr.forEach(num => result.push({num: num})) arr2.forEach(num => result.push({num: num}))
Map
let result = arr.map(num => {num: num}).concat(arr2.map(num => {num: num}))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
ForEach
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 is being tested, compared, and the pros and cons of each approach.

**Benchmark Description**

The benchmark is testing two approaches to create a new array by concatenating two existing arrays: `ForEach` and `Map`.

**Options Compared**

1. **ForEach**: Uses the `forEach` method to iterate over the elements of an array and push them into a new array.
2. **Map**: Uses the `map` method to create a new array by applying a transformation function to each element of an array.

**Pros and Cons of Each Approach**

* **ForEach**:
	+ Pros: Easy to understand, no additional library needed.
	+ Cons: Can be slower than `Map` for large datasets, as it involves more iterations over the original arrays.
* **Map**:
	+ Pros: Faster than `ForEach`, especially for large datasets, since it uses a single iteration and creates an array of transformed values.
	+ Cons: Requires understanding of map functions and can be less readable.

**Library Used**

Neither `ForEach` nor `Map` requires a separate library. They are built-in JavaScript methods.

**Special JS Feature/Syntax**

There is no special JavaScript feature or syntax used in this benchmark.

**Other Considerations**

* The test assumes that the input arrays (`arr` and `arr2`) have the same length.
* The benchmark measures the execution time of each approach, which can be influenced by factors such as the browser's caching mechanism, network latency, and system resources.

**Alternative Approaches**

1. **Reduce**: Instead of using `forEach` or `map`, one could use the `reduce` method to create a new array by summing up the elements of two arrays.
2. **Array.prototype.reduceRight()**: Similar to `reduce`, but iterates over the arrays in reverse order.

In summary, this benchmark tests the performance difference between using `forEach` and `map` to concatenate two arrays in JavaScript. The results suggest that `Map` is faster for large datasets, but require more expertise in JavaScript methods.

Related benchmarks:

ForEach vs Map for creating new array with concat (version: 0)

Comparing performance of: ForEach vs Map

Created: 5 years ago by: Guest

Jump to the latest result

ForEach

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):