Benchmark: Array slice, splice and direct access 2

Script Preparation code:

arr = [...Array(100000).keys()];
inds = [...Array(25000).keys()];

Tests:

Slice
res = inds.map(i => arr.slice(i*4, (i+1) *4));
Splice
res = [] for (const i of inds) { res.push(arr.splice(0,4)); }
Direct
res = inds.map(i => [arr[i*4], arr[(i*4)+1], arr[(i*4)+2], arr[(i*4)+3]]);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Slice
Splice
Direct

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model gemma2:9b, generated one year ago):

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This benchmark compares three different methods for accessing and manipulating arrays in JavaScript: using `slice()`, `splice()`, and direct array indexing.

Here's a breakdown:

* **Slice (`map(i => arr.slice(i*4, (i+1) *4))`)**: 
    - This method uses the `slice()` function to extract portions of the original array (`arr`).  The `map()` function iterates over a set of indices (`inds`), and for each index, it creates a new subarray using `slice()`. It effectively "slices" the original array into smaller chunks based on those indices.
    - **Pros:** Generally considered efficient and concise for extracting specific ranges of elements without modifying the original array.

* **Splice (`for...of` loop with `splice`)**: 
    - This method uses a `for...of` loop to iterate over the indices (`inds`). Within the loop, it employs the `splice()` function to extract a fixed number of elements (4 in this case) from the beginning of the original array. Each extracted portion is pushed into a new array (`res`).
    - **Pros:**  Directly modifies the original array, potentially leading to slightly better performance if you need to work with the modified array afterwards.

* **Direct Access (`map(i => [arr[i*4], arr[(i*4)+1], ...])`)**: 
    - This method uses direct indexing (e.g., `arr[i * 4]`) to access specific elements within the original array. It then creates a new subarray using those individual elements for each index in `inds`.

- **Pros:** Can be very efficient when accessing individual elements, especially if it avoids unnecessary loop iterations.

**Other Considerations**:
* **Performance Trade-offs:** The benchmark results likely reflect real-world performance differences between these methods.  `slice()` generally has a good balance of efficiency and clarity. `splice()` can be faster in certain scenarios but comes with the side effect of modifying the original array. Direct access can be very fast for individual element lookups but might not be as efficient if you need to process multiple elements together.
* **Conciseness:** `slice()` tends to be the most concise and readable approach for extracting subarrays.
* **Side Effects:** `splice()` modifies the original array, which can have unintended consequences if you don't manage it carefully.

**Alternatives:**

* **ES6 Array Methods:** Consider using more modern ES6 array methods like `filter`, `slice`, `map` and `reduce` to achieve similar results with potentially better performance.  These methods often take advantage of JavaScript's optimized internal mechanisms.
* **Libraries (e.g., Lodash):** For very complex array manipulations, libraries like Lodash can provide specialized functions that are more efficient and easier to use than writing everything by hand.

Let me know if you have any other questions!

Related benchmarks:

Array slice, splice and direct access 2 (version: 0)

Comparing performance of: Slice vs Splice vs Direct

Created: 3 years ago by: Guest

Jump to the latest result

Slice

Splice

Direct

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model gemma2:9b, generated one year ago):