Benchmark: slice vs new allocation2

Script Preparation code:

var arr = [];
for (let i = 0; i < 1000000; i++) {
  arr.push(i);
}

Tests:

Slice
for (let i = 0; i < 1000; i++) { arr.slice(i * 10, 1000) }
slice and save
const arr = []; for (let i = 0; i < 1000; i++) { arr.push(arr.slice(i * 10, 1000)) }
loop
for (let i = 0; i < 1000; i++) { }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Slice
slice and save
loop

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**What is tested?**

The provided JSON represents a benchmark test that compares three different approaches to allocating memory for an array:

1. **Slice**: Creating an empty array and then using the `slice()` method to allocate space for the desired range of elements.
2. **New Allocation with Slice**: Creating an empty array, pushing some initial elements, and then using the `slice()` method on that array to allocate space for the remaining elements.
3. **Loop**: Simply looping through the code without allocating any memory.

**Options compared**

The benchmark is comparing three different approaches:

* **Slice**: Using the `slice()` method to allocate memory for a range of elements in an existing array.
* **New Allocation with Slice**: Creating an empty array, pushing some initial elements, and then using the `slice()` method on that array to allocate space for the remaining elements.
* **Loop**: Simply looping through the code without allocating any memory.

**Pros and Cons**

Here's a brief summary of each approach:

* **Slice**:
	+ Pros: Fast and efficient way to allocate memory for an existing array.
	+ Cons: Assumes the original array has enough space allocated, which might not be the case if the array is too large.
* **New Allocation with Slice**:
	+ Pros: Allows for more control over the allocation process and can be useful when working with arrays of varying sizes.
	+ Cons: Creates unnecessary overhead by pushing initial elements onto the array before using `slice()`.
* **Loop**:
	+ Pros: Simplest approach that doesn't allocate any memory, which can be beneficial in terms of memory usage.
	+ Cons: Might not be as efficient as the other approaches due to potential CPU overhead from looping through code.

**Library and purpose**

There is no explicit library mentioned in the provided JSON. However, it's worth noting that some JavaScript engines might use internal libraries or heuristics when executing `slice()` method calls.

**Special JS feature or syntax**

There are a few special features or syntax elements present in the benchmark:

* **let i = 0;**: Declaring a variable using the `let` keyword, which is a modern JavaScript syntax introduced in ECMAScript 2015.
* `const arr = []`: Creating an empty array literal using the `const` keyword, which is also a modern JavaScript syntax introduced in ECMAScript 2015.

**Alternatives**

Other alternatives for benchmarking JavaScript performance might include:

* Using a different data structure, such as a linked list or a heap.
* Adding additional overhead to the benchmarks, such as I/O operations or network requests.
* Measuring performance on different types of hardware or operating systems.
* Using a more advanced benchmarking framework that provides more detailed information about execution times and memory usage.

In conclusion, the provided JSON represents a simple yet insightful benchmark test that compares three different approaches to allocating memory for an array in JavaScript. By understanding the pros and cons of each approach, developers can choose the most suitable method for their specific use case and optimize their code accordingly.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36

Browser/OS: Chrome 109 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Slice	11970.9 Ops/sec
slice and save	56939.1 Ops/sec
loop	3366701.0 Ops/sec

Related benchmarks:

slice vs new allocation2 (version: 0)

Comparing performance of: Slice vs slice and save vs loop

Created: one year ago by: Guest

Jump to the latest result

Slice

slice and save

loop

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):