Benchmark: set array index: slice vs Object.assign v2

Tests:

splice
var index = 2; var array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; var output = [ ...array.slice(0, index), 10, ...array.slice(index + 1) ];
Object.assign spread
var array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; var output = Object.assign([...array], {2: 10});
Object.assign slice
var array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; var output = Object.assign(array.slice(), {2: 10});
Object.assign orig
var array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; var output = Object.assign([...array], {2: 10});

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
splice
Object.assign spread
Object.assign slice
Object.assign orig

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.16; rv:86.0) Gecko/20100101 Firefox/86.0

Browser/OS: Firefox 86 on Mac OS X 10.16

View result in a separate tab

Test name	Executions per second
splice	1779697.6 Ops/sec
Object.assign spread	1691872.2 Ops/sec
Object.assign slice	3982847.2 Ops/sec
Object.assign orig	1767677.8 Ops/sec

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

LLMs can make mistakes. Check important info.

The provided benchmark measures the performance of three different approaches to modify an array in JavaScript:

1. **Slice**: This approach uses the `slice()` method to create a new array with a specified subset of elements from the original array. The test case creates a sample array and attempts to insert a value at index 2 using both `array.slice(0, index)` (exclusive) and `array.slice(index + 1)` (exclusive).

Pros:

* Easy to understand and implement
* Widely supported by most JavaScript engines

Cons:

* Creates a new array, which can lead to increased memory usage
* May not be as efficient for large arrays due to the overhead of creating a new array object

2. **Object.assign**: This approach uses the `Object.assign()` method to create a new object by merging multiple source objects into one. In this test case, it is used to merge an array with another object containing a single key-value pair.

Pros:

* Can be more efficient than slice for large arrays, as it avoids creating a new array object
* Supports spread syntax (new in ECMAScript 2015)

Cons:

* Requires a compatible browser or Node.js version that supports `Object.assign`
* May have performance implications when dealing with very large objects

3. **Spread operator**: This approach uses the spread operator (`...`) to create a new array by spreading elements from an existing array.

Pros:

* Similar syntax to Object.assign for merging arrays
* Supports modern browsers and Node.js versions (ECMAScript 2015 and later)

Cons:

* Requires a compatible browser or Node.js version that supports the spread operator

In this specific benchmark, the results show that:

* **Object.assign slice** performs best with an average execution rate of approximately 3.77 executions per second.
* **splice** is slower, with an average execution rate of around 1.76 executions per second.
* **Object.assign orig** and **Object.assign spread** have similar performance, with averages of about 1.70 and 1.69 executions per second, respectively.

The library used in the benchmark is none, as it only involves native JavaScript operations.

Related benchmarks:

set array index: slice vs Object.assign v2 (version: 0)

Comparing performance of: splice vs Object.assign spread vs Object.assign slice vs Object.assign orig

Created: 3 years ago by: Guest

Jump to the latest result

splice

Object.assign spread

Object.assign slice

Object.assign orig

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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