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

Tests:

spread operator
var test = ["hello", true, 7]; var copy = [...test];
Array.prototype.slice
var test = ["hello", true, 7]; var copy = test.slice();
Array.prototype.slice(0)
var test = ["hello", true, 7]; var copy = test.slice(0);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread operator
Array.prototype.slice
Array.prototype.slice(0)

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Firefox/78.0

Browser/OS: Firefox 78 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
spread operator	20610108.0 Ops/sec
Array.prototype.slice	23730614.0 Ops/sec
Array.prototype.slice(0)	23757460.0 Ops/sec

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

LLMs can make mistakes. Check important info.

The provided JSON represents a JavaScript microbenchmark test case on the MeasureThat.net website. The benchmark compares the performance of three methods for creating a shallow copy of an array: the new ES6 spread operator (`...`), `Array.prototype.slice()`, and `Array.prototype.slice(0)`.

**Options Compared:**

1. **Spread Operator (`...`)**: Creates a new array by iterating over the elements of the original array and adding them to the new array. This method is introduced in ECMAScript 2015 (ES6) and provides a concise way to create copies of arrays.
2. **`Array.prototype.slice()`**: Returns a shallow copy of a portion of an array, including the elements from the start index (0) up to but not including the end index. This method is commonly used for creating copies of arrays in JavaScript.
3. **`Array.prototype.slice(0)`**: Similar to `slice()`, but returns a copy of the entire array, starting from the first element and ending at the second-to-last element.

**Pros and Cons:**

1. **Spread Operator (`...`)**:
	* Pros: concise, readable, and efficient (since it creates a new array object).
	* Cons: not supported in older browsers (pre-ES6), may have performance issues with very large arrays.
2. **`Array.prototype.slice()`**:
	* Pros: widely supported across browsers and versions, relatively fast.
	* Cons: can be less readable than the spread operator or `slice(0)`, returns a reference to the original array if the end index is out of bounds.
3. **`Array.prototype.slice(0)`**:
	* Pros: creates an exact copy of the entire array, includes the use of `slice()` which is familiar to developers.
	* Cons: slower than the spread operator or `slice()` alone, returns a reference to the original array if not used carefully.

**Library/Functionality Used:**

In this benchmark, none of the methods rely on external libraries. However, it's worth noting that `Array.prototype.slice()` and `Array.prototype.slice(0)` are part of the built-in JavaScript API.

**Special JS Feature/Syntax:**

The spread operator (`...`) is a relatively new feature introduced in ECMAScript 2015 (ES6). It allows creating copies of arrays or objects by iterating over their elements. The syntax for using the spread operator varies depending on the target environment; in this benchmark, it's used as `var copy = [...test];`.

**Other Alternatives:**

For creating shallow copies of arrays, alternative methods include:

1. **`Array.prototype.concat()`**: Creates a new array by concatenating the elements of two or more arrays.
2. **`Array.from()`**: Creates a new array from an iterable or an array-like object.

These alternatives might have different performance characteristics and use cases compared to the spread operator, `slice()`, and `slice(0)` methods.

Related benchmarks:

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

Compare the new ES6 spread operator with the traditional slice() and slice(0) methods

Comparing performance of: spread operator vs Array.prototype.slice vs Array.prototype.slice(0)

Created: 4 years ago by: Guest

Jump to the latest result

spread operator

Array.prototype.slice

Array.prototype.slice(0)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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