Benchmark: flat vs concat test

Script Preparation code:

var arr = Array(1000).fill([0])

Tests:

concat
function flatten(arr) { return Array.prototype.concat.apply([], arr); } flatten(arr)
flat
arr.flat();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
concat
flat

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Windows

View result in a separate tab

Test name	Executions per second
concat	63544.5 Ops/sec
flat	67486.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the Benchmark Definition json and explain what is tested on the provided website.

**Benchmark Description**

The benchmark compares two approaches to flatten an array of arrays in JavaScript:

1. **`Array.prototype.concat.apply([], arr)`**: This approach uses the `concat()` method to concatenate all elements of the input array (`arr`) into a single array.
2. **`arr.flat()`**: This is a modern JavaScript feature introduced in ES6 (ECMAScript 2015) that provides a more concise way to flatten an array of arrays.

**Comparison Options**

The benchmark compares these two approaches because they have different performance characteristics and use cases:

* **`concat()`**:
	+ Pros: widely supported, can be used with older browsers.
	+ Cons: less efficient than `flat()`, requires explicit handling of nested arrays.
* **`arr.flat()`**:
	+ Pros: concise, efficient, and easy to read.
	+ Cons: only supported in modern browsers (ES6+) and may not work in older environments.

**Library Used**

In this benchmark, no library is explicitly used. However, the `concat()` method is a built-in JavaScript method that can be accessed through the `Array.prototype` object.

**Special JS Feature or Syntax**

The `arr.flat()` syntax uses the modern JavaScript feature called "array flattening" (introduced in ES6). This feature allows you to flatten an array of arrays into a single array using the `flat()` method.

**Other Considerations**

When choosing between these two approaches, consider the following factors:

* **Performance**: If you need high performance and support for older browsers, use `concat()`. For better performance and modern browser support, use `arr.flat()`.
* **Readability**: If code readability is crucial, use `arr.flat()` as it is more concise and readable.

**Alternatives**

If the provided benchmark results are not satisfactory or if you need to compare other approaches, consider using alternative methods:

1. **Using `for...of` loop**: This approach can be used with both modern browsers (ES6+) and older environments.
2. **Using recursion**: A recursive function can be defined to flatten an array of arrays.
3. **Using a third-party library**: Some libraries, like Lodash, provide functions for flattening arrays.

Keep in mind that the choice of alternative approach depends on your specific requirements and constraints.

Related benchmarks:

flat vs concat test (version: 3)

Comparing performance of: concat vs flat

Created: 3 years ago by: Registered User

Jump to the latest result

concat

flat

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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