Benchmark: slice vs spread performance

Script Preparation code:

var params = Array.from({
    length: 123
}, () => ({
    a1: Math.random(),
    a2: Math.random(),
    a3: Math.random(),
    qwer: `Hello ${Math.random()}`
}))

Tests:

Array.prototype.slice
const other = params.slice();
spread operator
const other = [ ...params ]

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:

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

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Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Overview**

The benchmark, titled "slice vs spread performance", compares the performance of two methods: `Array.prototype.slice()` and the new ES6 spread operator (`[ ...params ]`). The benchmark creates an array of 123 objects with random properties (including a string that concatenates a random number) using the provided script preparation code.

**Options Compared**

The benchmark tests two options:

1. **`Array.prototype.slice()`**: This method returns a shallow copy of a portion of an array, starting from the specified index and taking a given length.
2. **ES6 spread operator (`[ ...params ]`)**: This operator creates a new array by spreading the elements of an existing array or iterable.

**Pros and Cons**

1. **`Array.prototype.slice()`**:
	* Pros: widely supported, easy to understand, and has been around for a long time.
	* Cons: can be slower than other methods, as it involves creating a new array object.
2. **ES6 spread operator (`[ ...params ]`)**:
	* Pros: generally faster, more concise, and easier to read, especially when working with small arrays or iterables.
	* Cons: may not work as expected for large arrays or complex iterables, and some older browsers might not support it.

**Library/Utility Functions**

None are explicitly mentioned in this benchmark. However, the spread operator relies on the `Array.prototype` and the spread syntax (`[ ...iterable ]`), which is a built-in JavaScript feature.

**Special JS Features/Syntax**

The ES6 spread operator uses the following special syntax:

* The `...` spread operator.
* Array destructuring syntax (not explicitly used in this benchmark, but implied by the use of `[ ...params ]`).

**Other Considerations**

When choosing between these two methods, consider the size and complexity of your array, as well as performance requirements. For small arrays or simple cases, the ES6 spread operator might be a better choice due to its conciseness and ease of use. However, for larger datasets or performance-critical code, `Array.prototype.slice()` might still be a safer option.

**Alternatives**

Other methods that could be used instead of `Array.prototype.slice()` include:

* `Array.from()`: Creates a new array from an iterable.
* Custom implementation using `slice()` with a loop: `var result = []; for (var i = 0; i < length; i++) { result.push(obj[i]); }`.

Keep in mind that these alternatives might have different performance characteristics and use cases.

Related benchmarks:

slice vs spread performance (version: 0)

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

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

Created: 2 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

No previous run results

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