Benchmark: slice vs get by index

Script Preparation code:

var array = [1,2,3,4,5]

Tests:

slice
var newArray = array.slice(1, 4)
get by index
var newArray = [array[1], array[2], array[3]]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
get by index

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

Let's break down what is tested in the provided JSON for the MeasureThat.net benchmark.

The test compares two approaches to get items from an array:

1.  **Array.prototype.slice()**: This method returns a shallow copy of a portion of an array, originating at the specified start index and ending at (but not including) the specified end index.
2.  **Manual indexing**: This approach manually extracts specific elements from the original array by their indices.

**Comparison Options:**

*   `slice`: Uses Array.prototype.slice() to create a new array with a subset of elements from the original array.
*   `get by index`: Manually extracts individual elements from the original array using array indexing (e.g., `array[1]`, `array[2]`, etc.).

**Pros and Cons:**

*   **slice**: Pros:
    *   More concise and readable code
    *   No manual indexing required, which can reduce errors
*   Cons:
    *   Creates a new array, which may consume more memory
    *   May be slower than manual indexing in some cases (depending on the browser's optimization)
*   **get by index**: Pros:
    *   More control over the extracted elements and their order
    *   Potentially faster than slice in some cases due to reduced overhead
*   Cons:
    *   More verbose code that may be harder to read
    *   Requires manual indexing, which can increase errors

**Library/Functionality Used:**

None of the provided options use any external libraries or functions beyond standard JavaScript. The tests only rely on built-in array methods and basic arithmetic operations.

**Special JS Feature/Syntax (Not Applicable):**

Since this test doesn't involve any special JavaScript features or syntax, we won't explore that further.

**Other Alternatives:**

In addition to the two approaches mentioned above, other alternatives might include:

*   **Array.prototype.map()**: This method creates a new array with the results of applying a provided function on every element in this array. While not directly comparable to slice or manual indexing, it could potentially be used for similar purposes.
*   **Destructuring assignment**: This syntax allows you to extract multiple values from an array into variables in a single statement (e.g., `const [newArray[1], newArray[2]] = array.slice(1, 4)`). While not exactly equivalent to slice or manual indexing, it provides an alternative way to work with arrays.

Please note that these alternatives are not directly applicable to the specific test case provided and might require additional modifications to be used.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Linux; Android 10; RMX1911) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.85 Mobile Safari/537.36

Browser/OS: Chrome Mobile 94 on Android

View result in a separate tab

Test name	Executions per second
slice	2339930.2 Ops/sec
get by index	1160364.8 Ops/sec

Related benchmarks:

slice vs get by index (version: 0)

Comparison of Array.prototype.slice and manually getting items by index

Comparing performance of: slice vs get by index

Created: 2 years ago by: Guest

Jump to the latest result

slice

get by index

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):