Benchmark: Array slice vs for loop

Script Preparation code:

var data = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0];

Tests:

slice
var copy = data.slice(3, 8);
push
var copy = []; for (var i = 3; i < 8; i++) { copy.push(data[i]) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
push

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:150.0) Gecko/20100101 Firefox/150.0

Browser/OS: Firefox 150 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
slice	93228872.0 Ops/sec
push	169184240.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and analyze what is being tested.

**Benchmark Description**

The benchmark is designed to compare the performance of two approaches: using `Array.slice()` versus using a traditional `for` loop to create a copy of an array slice.

**Script Preparation Code**

The script preparation code sets up a sample data array with 10 elements, which will be used as the input for both test cases. This ensures that both tests have the same starting point and are measuring the performance difference between the two approaches.

**Options Being Compared**

There are two options being compared:

1. **`Array.slice()`**: This method creates a new array containing a subset of elements from the original array, without modifying the original array.
2. **Traditional `for` loop with `push()`**: This approach uses a traditional `for` loop to iterate over the desired range of elements in the original array and pushes each element onto a new array.

**Pros and Cons**

Here are some pros and cons of each approach:

**`Array.slice()`**:

Pros:

* More concise and readable code
* Less chance of errors due to manual indexing
* Performance is often comparable to other methods (e.g., `slice()` uses optimized C++ code)

Cons:

* May not be as efficient in certain cases (e.g., very large arrays)
* Can create a new array object, which may consume more memory

**Traditional `for` loop with `push()`**:

Pros:

* Can be more efficient for very large arrays
* Allows for manual control over the iteration process

Cons:

* More verbose code, making it harder to read and maintain
* Risk of errors due to manual indexing or off-by-one issues

**Library Used: None**

There is no library being used in this benchmark. The `Array.slice()` method is a built-in JavaScript method, while the traditional `for` loop with `push()` is a standard JavaScript construct.

**Special JS Feature/Syntax: None**

There are no special JavaScript features or syntax being tested in this benchmark.

**Other Considerations**

When comparing performance between these two approaches, it's essential to consider factors such as:

* Array size and shape
* Browser and platform compatibility
* Memory allocation and deallocation overhead

In general, `Array.slice()` is a safe choice when conciseness and readability are more important than raw performance. However, for very large arrays or specific use cases where manual control is required, the traditional `for` loop with `push()` might be a better option.

**Alternatives**

Other alternatives to consider when creating JavaScript benchmarks include:

* Using Web Worker threads for parallel execution
* Utilizing modern JavaScript features like `Array.from()`, `Array.prototype.reduce()`, or `map()`
* Considering other data structures, such as buffers or TypedArrays

Related benchmarks:

Array slice vs for loop (version: 0)

Comparing performance of: slice vs push

Created: 6 years ago by: Guest

Jump to the latest result

slice

push

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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