Benchmark: Array.prototype.slice vs spread operator.

Script Preparation code:

var a = [ "hello", true, 7 ];

Tests:

Array.prototype.slice
var b = a.slice();
spread operator
var b = [ ...a ]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.prototype.slice
spread operator

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 28 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:149.0) Gecko/20100101 Firefox/149.0

Browser/OS: Firefox 149 on Windows

View result in a separate tab

Test name	Executions per second
Array.prototype.slice	66216792.0 Ops/sec
spread operator	62067904.0 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 world of JavaScript benchmarking.

**Benchmark Definition and Purpose**
The provided JSON represents a simple benchmark that compares two approaches to create a shallow copy of an array: `Array.prototype.slice()` vs the ES6 spread operator (`[ ...a ]`).

**Options Compared**

1. **Array.prototype.slice()**: This method returns a new, shallow copy of the specified portion of an array.
2. **ES6 Spread Operator (`[ ...a ]`)**: This syntax creates a new array with elements taken from the original array.

**Pros and Cons**

* `Array.prototype.slice()`:
	+ Pros: widely supported across browsers, efficient in most cases.
	+ Cons: can be slower than the spread operator for large arrays due to the overhead of creating a new function.
* ES6 Spread Operator (`[ ...a ]`):
	+ Pros: concise and expressive syntax, can be faster than `slice()` for large arrays.
	+ Cons: not supported in older browsers or versions (pre-ES6), may lead to slower performance in some cases.

**Library and Purpose**
None in this specific benchmark. However, the spread operator relies on the `Symbol.iterator` and `Array.prototype.forEach` methods internally, which are built-in JavaScript features.

**Special JS Feature/Syntax**
The ES6 spread operator (`[ ...a ]`) uses a new syntax feature introduced by ECMAScript 2015 (ES6). This feature allows for concise array creation using the `...` operator.

**Other Considerations**

* The benchmark results show that Chrome 84 on a Desktop Mac OS X 10.15.6 achieves significantly higher execution frequencies per second for both test cases compared to other browsers or platforms.
* To make this benchmark more comprehensive, you could consider adding tests for other JavaScript engines (e.g., Node.js), older browsers, or additional array operations.

**Alternatives**

1. **Benchmarking frameworks**: For more complex benchmarks, consider using dedicated benchmarking frameworks like BenchmarkJS or Benchmark-chrome.
2. **Test cases**: Consider adding more test cases to cover different scenarios, such as:
	* Larger arrays
	* Nested arrays
	* Objects with nested properties
	* Array operations (e.g., `map()`, `filter()`)

By expanding the benchmark suite and considering various factors, you can gain a better understanding of your JavaScript code's performance characteristics.

Related benchmarks:

Array.prototype.slice vs spread operator. (version: 0)

Compare the ES6 spread operator with the traditional slice() method

Comparing performance of: Array.prototype.slice vs spread operator

Created: 5 years ago by: Guest

Jump to the latest result

Array.prototype.slice

spread operator

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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