Benchmark: splice vs length

Tests:

splice
var a = [0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9] a.splice(200)
length
var a = [0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9] a.length = 200

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
splice
length

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

Measuring the performance of JavaScript operations is crucial for understanding how different browsers and devices handle various tasks efficiently.

The benchmark you provided measures two distinct approaches to working with arrays in JavaScript:

1.  **Using `splice()`**: This operation modifies the original array by removing or replacing elements, shifting all subsequent elements down to fill the gap.
2.  **Accessing the length property directly (`length`)**: Instead of using `splice()`, this approach accesses the length of an array using its own property.

Now let's explore the pros and cons of each:

### Using `splice()`

*   Pros:
    *   It can be used to both modify and remove elements from an array.
    *   Allows for more complex operations, such as inserting or replacing specific elements in a specified position.
*   Cons:
    *   Modifying an array using `splice()` can lead to unnecessary reallocations of the underlying array data structure. This can result in slower performance due to the increased number of allocations and deallocations.

### Accessing the length property directly (`length`)

*   Pros:
    *   More memory-efficient than modifying the original array, as it doesn't require additional allocations.
    *   Faster execution time because it only involves accessing a property on the object.
*   Cons:
    *   Only allows for reading the current size of an array; you cannot modify the length.

To choose between these two approaches:

*   Use `splice()` if you need to perform operations that involve modifying or inserting elements into your array.
*   Accessing `length` is a good option when you just want to read the current number of items in an array without modifying it.

**Other Alternatives and Considerations**

*   **For loop vs. forEach**: In some cases, using a traditional for loop might outperform a for-each loop because modern browsers have optimized their internal iteration engines. However, the difference is usually negligible.
*   **Array operations vs. direct access to object properties**: Some JavaScript libraries or frameworks provide methods to optimize common array operations (e.g., map(), filter(), reduce()). Using these methods directly can sometimes offer better performance due to their ability to utilize specialized optimized algorithms.

**Library Used**

The provided test case doesn't explicitly mention a specific library, but it appears that MeasuringThat.net uses a JavaScript interpreter or engine to execute the benchmarks. The execution results are reported as UAspString (a unique identifier for each browser instance), and they seem to be based on Firefox 107.

**Special JS Features**

MeasuringThat.net does not specifically mention any special JavaScript features like async/await, promises, or ES6+ syntax in its test case.

However, please note that JavaScript performance can be influenced by the engine used and may vary depending on factors such as hardware capabilities, browser configuration, and other environment-specific conditions.

Related benchmarks:

splice vs length (version: 0)

Comparing performance of: splice vs length

Created: 4 years ago by: Guest

Jump to the latest result

splice

length

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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