Benchmark: unshift vs swapping

Script Preparation code:

var arr = [...Array(10000)].map((_,i) => i)

Tests:

unshift
arr.unshift(arr.splice(500,1).shift())
swapping
arr.sort((a,b) => a === 500 ? -1 : 0)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
unshift
swapping

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 llama3.1:latest, generated one year ago):

LLMs can make mistakes. Check important info.

Let's dive into the benchmark definition.

**What is being tested?**

The benchmark tests two different approaches to replace the middle element of an array:

1. **`unshift`**: This approach uses the `unshift()` method to add an element at the beginning of the array, effectively replacing the first element.
2. **Swapping**: This approach uses the `sort()` method with a custom comparison function to swap the middle element with the correct one.

**What options are compared?**

In this benchmark, two options are being compared:

* The performance of using `unshift()` to add an element at the beginning of the array.
* The performance of using `sort()` with a custom comparison function to swap the middle element.

**Pros and Cons:**

Here's a brief summary of the pros and cons of each approach:

* **`unshift()`**: Pros:
	+ Simple and concise implementation.
	+ Does not modify the original array order for elements outside the unshifting range.
*   Cons:
    + May cause the entire array to be recreated, leading to memory overhead and potential performance issues.
* **Swapping (sort() with custom comparison)**: Pros:
	+ More efficient in terms of memory usage and array modification.
	+ Can be used for more complex operations like sorting.
*   Cons:
    + Has a higher cognitive complexity due to the custom comparison function.
    + May not perform well on large arrays.

**Library Used**

No external libraries are being used in this benchmark. The JavaScript methods `unshift()`, `sort()`, and `splice()` are native to the language.

**Special JS Feature or Syntax**

The only special feature used is the `sort()` method with a custom comparison function, which is defined as `(a,b) => a === 500 ? -1 : 0`. This syntax uses an arrow function expression (introduced in ECMAScript 2015) to define the comparison function. The comparison function itself is quite simple and only checks if `a` is equal to 500, returning `-1` if true or `0` otherwise.

**Other Alternatives**

While not directly compared in this benchmark, other alternatives for replacing the middle element of an array could include:

* Using a `slice()` method to remove the middle element and then concatenating the remaining elements.
* Implementing a custom swap function using array indexing and assignment.
* Utilizing more advanced data structures like linked lists or trees.

Keep in mind that these alternatives may have their own trade-offs, performance characteristics, and use cases.

Related benchmarks:

unshift vs swapping (version: 0)

Comparing performance of: unshift vs swapping

Created: 6 years ago by: Guest

Jump to the latest result

unshift

swapping

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):