Benchmark: slice vs subarray destructuring

Script Preparation code:

var bytes = [84,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46,104,105,115,32,105,115,32,97,32,115,97,109,112,108,101,32,112,97,114,97,103,114,97,112,104,46];
var buffer = new ArrayBuffer(bytes);
var bufferArray = new Uint8Array(bytes);
var s;

Tests:

slice
var [a,b,c,d] = bufferArray.slice(43, 47); s = a + b + c + d;
subarray
var [a,b,c,d] = bufferArray.subarray(43, 47); s = a + b + c + d;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
subarray

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 12 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36 Edg/133.0.0.0

Browser/OS: Chrome 133 on Windows

View result in a separate tab

Test name	Executions per second
slice	2883161.8 Ops/sec
subarray	2960071.5 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 12 days ago):

LLMs can make mistakes. Check important info.

The benchmark provided evaluates the performance differences between two methods of extracting a subset of data from a typed array in JavaScript: the `slice` method and the `subarray` method. Here's a detailed breakdown of what's being tested, the options compared, their pros and cons, and other considerations.

### What is Tested

The benchmark consists of two test cases, each using a different method to extract values from a `Uint8Array` which is a typed array that represents an array of 8-bit unsigned integers. The slice of the array is defined by the indices 43 to 47, and the extracted values (a, b, c, and d) are added together to generate a final result.

1. **slice Method**:
   ```javascript
   var [a,b,c,d] = bufferArray.slice(43, 47);
   s = a + b + c + d;
   ```

2. **subarray Method**:
   ```javascript
   var [a,b,c,d] = bufferArray.subarray(43, 47);
   s = a + b + c + d;
   ```

### Options Compared

- **slice**: The `slice` method creates a new array by copying the selected elements from the original array, which can result in additional memory overhead.
- **subarray**: The `subarray` method, on the other hand, creates a new view on the original array without copying the data. It points to the same underlying data buffer, and thus there is less memory overhead associated with this method.

### Pros and Cons

#### slice
**Pros**:
- Returns a standard array (not a typed array), which can be useful if you need to operate on a general array.

**Cons**:
- Creates a duplicate of the sliced data, which can lead to increased memory usage, especially for large arrays.
- Can be slower due to the overhead of copying data.

#### subarray
**Pros**:
- More efficient in terms of memory usage, as it does not create a copy of the data but rather a view of the original array.
- Generally faster than `slice`, as it requires less processing to create the subarray.

**Cons**:
- Returns a typed array (in this case, `Uint8Array`), which may not be suitable if a standard array is expected.
- Changes to the data in the original array are reflected in the subarray, which could lead to unintended side effects if shared data is modified.

### Other Considerations

- **Performance**: The benchmark results showed that `subarray` executed with a higher number of operations per second than `slice`, indicating better performance.
- **Use Case**: Choosing between `slice` and `subarray` depends on whether you require a copy of the elements or a view that might be affected by future changes to the original array.
- **Typed Arrays**: Both methods are applied to typed arrays, which provide a way to work with binary data, allowing for more control over memory and performance compared to standard JavaScript arrays.

### Alternatives

1. **Using Standard Arrays**: A programmer could convert the typed array to a standard array, then use `slice`. However, this approach sacrifices the performance benefits of typed arrays and incurs overhead due to copying.

2. **Manual Copying**: Another alternative could be manually iterating through the indices and pushing elements into a new array. This would be less efficient and would typically have worse performance compared to both `slice` and `subarray`.

3. **Other Typed Array Methods**: Depending on the scenario, other methods on typed arrays, such as `map`, `filter`, or even custom aggregation functions, could be considered for different types of data manipulation.

In summary, this benchmark highlights the performance comparison of two common methods used to extract portions of data from typed arrays in JavaScript, providing insights that can guide developers in optimizing their code according to the specific requirements of their applications.

Related benchmarks:

slice vs subarray destructuring (version: 1)

Comparing performance of: slice vs subarray

Created: 12 days ago by: Guest

Jump to the latest result

slice

subarray

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 12 days ago):