Benchmark: lodash partition vs forEach with array spread iterator vs array push vs for each with concat vs two filters

HTML Preparation code:

<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js'></script>

Script Preparation code:

var tabl = Array.from({ length: 100000 }).map((value, i) => i)

Tests:

Lodash partition
let result = _.partition(tabl, v => v%2)
forEach with push
let a = [], b = []; let result = tabl.forEach(item => {if (item%2) {a.push(item)} else {b.push(item)}})
forEach with spread
let a = [], b = []; let result = tabl.forEach(item => {if (item%2) {a = [...a, item]} else {b = [...b, item]}})
forEach with concat
let a = [], b = []; let result = tabl.forEach(item => {if (item%2) {a = a.concat(item)} else {b = b.concat(item)}})
two filters
a = tabl.filter(item => item % 2) b = tabl.filter(item => !item % 2)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Lodash partition
forEach with push
forEach with spread
forEach with concat
two filters

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

Let's dive into explaining the provided benchmark and its various test cases.

**Benchmark Overview**

MeasureThat.net is a website where users can create and run JavaScript microbenchmarks. The provided JSON represents a benchmark that compares different approaches to partition an array in JavaScript using the `lodash` library, as well as three other approaches without using any external libraries.

**Test Cases**

There are four test cases:

1. **Lodash Partition**: This test case uses the `partition` function from the `lodash` library to divide an array into two parts based on a given predicate.
2. **ForEach with Push**: This test case iterates over an array using the `forEach` method and pushes elements to separate arrays based on a condition.
3. **ForEach with Spread**: Similar to the previous test case, but instead of pushing elements directly, it uses the spread operator (`...`) to create new arrays.
4. **ForEach with Concat**: This test case iterates over an array using `forEach` and concatenates elements to separate arrays.
5. **Two Filters**: This test case uses two separate `filter` functions to achieve the same result as the previous three test cases.

**Options Comparison**

The different approaches have varying performance characteristics:

* **Lodash Partition**: The `partition` function is a built-in function in Lodash, and it's optimized for performance. It returns two arrays of equal length, which can be beneficial when working with large datasets.
* **ForEach with Push**: This approach can lead to slower performance because it involves iterating over the array multiple times (once for each array). Additionally, pushing elements to an array using `push` can be inefficient due to the overhead of resizing the array.
* **ForEach with Spread**: Using the spread operator (`...`) creates a new array, which can be expensive in terms of memory allocation and garbage collection. However, it's often more readable and concise than other approaches.
* **ForEach with Concat**: This approach involves concatenating arrays using `concat`, which can lead to slower performance due to the overhead of creating a new array.

**Pros and Cons**

Here are some pros and cons for each approach:

* **Lodash Partition**:
	+ Pros: Optimized for performance, returns two arrays of equal length.
	+ Cons: Only works with Lodash library.
* **ForEach with Push**:
	+ Pros: None notable.
	+ Cons: Can be slower due to multiple iterations and resizing the array.
* **ForEach with Spread**:
	+ Pros: Concise, readable code.
	+ Cons: Creates a new array, can lead to memory allocation issues.
* **ForEach with Concat**:
	+ Pros: None notable.
	+ Cons: Can be slower due to concatenation overhead.

**Other Considerations**

When choosing an approach, consider the following factors:

* Readability and maintainability of the code
* Performance requirements for your specific use case
* Library dependencies (in this case, Lodash)
* Memory allocation and garbage collection implications

**Alternatives**

If you're looking for alternative approaches to partitioning arrays in JavaScript without using libraries like Lodash, consider the following:

* Using `Array.prototype.filter()` with a callback function
* Implementing your own partition algorithm from scratch (e.g., using bitwise operations)
* Utilizing modern JavaScript features like async/await and iterators

Keep in mind that these alternatives may not offer the same level of performance or convenience as the tested approaches.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36

Browser/OS: Chrome 111 on Windows

View result in a separate tab

Test name	Executions per second
Lodash partition	964.9 Ops/sec
forEach with push	466.9 Ops/sec
forEach with spread	0.1 Ops/sec
forEach with concat	0.1 Ops/sec
two filters	409.0 Ops/sec

Related benchmarks:

lodash partition vs forEach with array spread iterator vs array push vs for each with concat vs two filters (version: 0)

Comparing performance of: Lodash partition vs forEach with push vs forEach with spread vs forEach with concat vs two filters

Created: one year ago by: Guest

Jump to the latest result

Lodash partition

forEach with push

forEach with spread

forEach with concat

two filters

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):