Benchmark: spread vs slice vs splice vs concat

Tests:

Splice
const arr1 = [ true, 1, "true", [], {}, function () {} ]; const arr2 = arr1.splice(0);
Slice
const arr1 = [ true, 1, "true", [], {}, function () {} ]; const arr2 = arr1.slice();
Concat
const arr1 = [ true, 1, "true", [], {}, function () {} ]; const arr2 = arr1.concat();
Spread
const arr1 = [ true, 1, "true", [], {}, function () {} ]; const arr2 = [...arr1];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Splice
Slice
Concat
Spread

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 break down the provided benchmark and explain what's being tested, the different approaches compared, their pros and cons, and other considerations.

**What is being tested?**

The benchmark is comparing the performance of four different methods to manipulate an array:

1. `splice`: Removing elements from the beginning of the array.
2. `slice`: Creating a shallow copy of a portion of the array.
3. `concat`: Concatenating two arrays.
4. `spread`: Using the spread operator (`...`) to create a new array.

**Approaches compared**

Each approach has its own advantages and disadvantages:

1. **`splice`**: This method is simple and intuitive, but it can be slow because it modifies the original array and creates a new copy of the remaining elements.
2. **`slice`**: Creating a shallow copy of an array using `slice()` is faster than `splice` because it only creates a new reference to the existing elements.
3. **`concat`**: Concatenating two arrays using `concat()` creates new arrays and copies the elements, which can be slower than other methods for large datasets.
4. **`spread`**: The spread operator (`...`) is a modern JavaScript feature that creates a new array by copying the elements from an existing array or object. It's generally faster and more efficient than the other methods.

**Pros and Cons**

* `splice`: Pros: simple, intuitive; Cons: can be slow, modifies original array.
* `slice`: Pros: fast, creates shallow copy; Cons: only creates reference to existing elements, not a new copy.
* `concat`: Pros: easy to use; Cons: creates new arrays, slows down for large datasets.
* `spread`: Pros: modern, efficient, creates new array; Cons: requires JavaScript 5.6+ support.

**Other considerations**

* The benchmark is running on an Android tablet with Firefox 68.0.
* The test cases are designed to measure the performance of each method in different scenarios (e.g., removing elements from the beginning of the array).
* The `function () {}` object is likely used as a placeholder to ensure that the methods being tested create new objects or arrays.

**Libraries and Special JS features**

None of the test cases use any libraries, but they do utilize JavaScript's built-in array and object methods.

**Special JS features**

The spread operator (`...`) is a relatively recent feature in JavaScript (introduced in ECMAScript 2015). If your target audience includes older browsers or environments without this support, you may need to use an alternative method or polyfill.

Other alternatives for creating new arrays include:

* `Array.prototype.map()`: Creates a new array by applying a mapping function to each element of the original array.
* `Array.prototype.filter()`: Creates a new array by filtering elements from the original array based on a predicate function.
* Using the `Array.from()` method with an iterable or array-like object.

Keep in mind that these alternatives may have different performance characteristics and use cases compared to the methods being tested in this benchmark.

Latest run results:

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

User agent: Mozilla/5.0 (Android 4.2.2; Tablet; rv:68.0) Gecko/68.0 Firefox/68.0

Browser/OS: Android 4 on Android 4.2.2

View result in a separate tab

Test name	Executions per second
Splice	224618.1 Ops/sec
Slice	507921.3 Ops/sec
Concat	529181.6 Ops/sec
Spread	453474.2 Ops/sec

Related benchmarks:

spread vs slice vs splice vs concat (version: 0)

Comparing performance of: Splice vs Slice vs Concat vs Spread

Created: 2 years ago by: Guest

Jump to the latest result

Splice

Slice

Concat

Spread

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):