Benchmark: Array.prototype.slice vs spread op

Tests:

slice
const a = Array.from({ length: 10000 }); a.slice();
spread
const a = Array.from({ length: 10000 }); [...a];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
spread

Fastest: N/A

Slowest: N/A

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

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Let's break down the provided benchmark and explain what's being tested, compared options, pros and cons, and other considerations.

**What is being tested?**

The benchmark measures the performance difference between two approaches:

1. `Array.prototype.slice()`: This method creates a shallow copy of a portion of an array.
2. The spread operator (`[...array]`): This syntax creates a new array by spreading the elements of an existing array.

**Options compared:**

* Two different approaches for creating a subset of an array: `slice()` and the spread operator.

**Pros and Cons of each approach:**

1. **Array.prototype.slice()**:
	* Pros:
		+ Well-supported across most browsers.
		+ Can be used with older browsers that don't support the spread operator.
	* Cons:
		+ Creates a new array object, which can lead to increased memory usage.
		+ May not be as efficient as other methods (like `Array.prototype.subarray()` or C-style indexing) for large arrays.
2. **Spread operator (`[...array]`)**:
	* Pros:
		+ More concise and expressive than `slice()`.
		+ Creates a new array object, which can lead to increased memory usage if not used carefully.
	* Cons:
		+ Not supported in older browsers ( prior to IE 11).
		+ May be slower than `slice()` for very large arrays due to the overhead of creating an iterator.

**Library and special JS feature:**

There is no library being tested in this benchmark. However, the spread operator (`[...array]`) is a new syntax introduced in ECMAScript 2015 (ES6), which allows for more concise array creation. This syntax has become widely adopted, but may not be supported by all browsers.

**Other considerations:**

* The test case uses an empty object with `length: 10000` to create a large array.
* The benchmark measures the execution time of each approach in terms of "ExecutionsPerSecond".
* The test results are likely to show that the spread operator is slower than `slice()` due to its additional overhead.

**Alternatives:**

If you need to perform subset operations on arrays, consider using other methods like:

* `Array.prototype.subarray()`: This method creates a new array object with a portion of another array.
* C-style indexing (`arr.slice(start, end)`): This approach can be faster and more memory-efficient than the spread operator or `slice()` for very large arrays.

Keep in mind that the choice of approach depends on your specific use case, the requirements of your project, and the support needed for different browsers.

Related benchmarks:

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

Comparing performance of: slice vs spread

Created: 3 years ago by: Guest

Jump to the latest result

slice

spread

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):