Benchmark: Slice vs Splice vs Shift

Script Preparation code:

var array = [1, 2, 3, 4, 5, 6, 7, 8]
var itemsToRemove = 2

Tests:

array.slice()
array = array.slice(2)
array.splice()
array.splice(0, itemsToRemove)
array.shift()
for (let i = 0 ; i < itemsToRemove ; i++) array.shift()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
array.slice()
array.splice()
array.shift()

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/147.0.0.0 Safari/537.36 Edg/147.0.0.0

Browser/OS: Chrome 147 on Windows

View result in a separate tab

Test name	Executions per second
array.slice()	7841607.5 Ops/sec
array.splice()	18275440.0 Ops/sec
array.shift()	13345268.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark.

**What is being compared?**

The benchmark is comparing three different ways to remove the first two elements from an array:

1. Using `slice()`
2. Using `splice()`
3. Using `shift()` (in a loop)

**What are the pros and cons of each approach?**

### 1. Array.slice()

* **Pros:**
	+ Easy to use, concise code
	+ Works well when you need to remove elements from anywhere in the array, not just the beginning
* **Cons:**
	+ Can be slower than `splice()` or `shift()`, especially for large arrays (as seen in the benchmark results)

### 2. Array.splice()

* **Pros:**
	+ Fast and efficient, especially for large arrays
	+ Allows you to remove elements from anywhere in the array, not just the beginning
* **Cons:**
	+ Can be slower than `shift()` when removing elements from the end of a small array (although this is unlikely)
	+ Requires specifying the index and count of elements to remove

### 3. Array.shift()

* **Pros:**
	+ Fast and efficient, especially for small arrays
	+ Easy to use in a loop when you need to remove multiple elements from the beginning of an array
* **Cons:**
	+ Only works when removing elements from the beginning of the array
	+ Can be slower than `splice()` or `slice()` when working with large arrays

**Library used**

None. The benchmark is using only built-in JavaScript methods (`slice()`, `splice()`, and `shift()`).

**Special JS feature or syntax**

None.

**Other alternatives**

* You can use the spread operator (`...`) in combination with `slice()` to remove elements, like this: `[...array.slice(2)]`.
* You can also use a loop with `delete` to remove elements from the array, but this approach is generally slower and less efficient than using `splice()` or `shift()`.
* If you need to remove elements from anywhere in the array, you can use a combination of `indexOf()` and `slice()` to find the index of the element to remove.

Overall, the benchmark results suggest that `splice()` is the fastest method for removing elements from an array, followed closely by `shift()`. However, when working with small arrays or specific use cases, `slice()` may still be a good choice due to its ease of use and concise code.

Related benchmarks:

Slice vs Splice vs Shift (version: 0)

Compares the speed for removing 2 items from the beginning of an array

Comparing performance of: array.slice() vs array.splice() vs array.shift()

Created: 5 years ago by: Guest

Jump to the latest result

array.slice()

array.splice()

array.shift()

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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