Benchmark: Slice vs Splice vs Shift (100)

Script Preparation code:

var array = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200]
var itemsToRemove = 100

Tests:

array.slice()
var narray = array.slice(itemsToRemove)
array.splice()
var narray = array.splice(0, itemsToRemove)
array.shift()
var narray = []; for (let i = 0 ; i < itemsToRemove ; i++) narray.push(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: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/117.0

Browser/OS: Firefox 117 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
array.slice()	7105294.5 Ops/sec
array.splice()	13915588.0 Ops/sec
array.shift()	781259.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring the performance of different array methods is an essential task for any JavaScript developer.

**Benchmark Overview**

The benchmark compares three ways to remove elements from the beginning of an array: `slice()`, `splice()`, and `shift()`.

**Methods Compared**

1. `array.slice(itemsToRemove)`: This method returns a new array containing the last `itemsToRemove` elements of the original array, effectively removing the first `itemsToRemove` elements.
2. `array.splice(0, itemsToRemove)`: This method modifies the original array by removing the first `itemsToRemove` elements and returns an array containing the removed elements.
3. `for (let i = 0 ; i < itemsToRemove ; i++) narray.push(array.shift())`: This method uses a loop to remove each of the first `itemsToRemove` elements from the original array using `shift()` and adds them to a new array (`narray`) until all elements are removed.

**Pros and Cons**

1. **slice()**: Pros: efficient, simple, and widely supported. Cons: returns a new array, can be slower for large arrays due to memory allocation.
2. **splice()**: Pros: modifies the original array, can be faster than `slice()` for large arrays. Cons: requires modifying the original array, can be less predictable behavior if not used carefully.
3. **shift() + loop**: Pros: flexible, can handle arrays of any size. Cons: slower and more complex than `slice()` or `splice()`, may cause stack overflow for very large arrays.

**Library Used**

None.

**Special JS Features/Syntax**

* None mentioned in the benchmark definition or test cases.

**Other Alternatives**

For array removal methods, you can also consider:

1. `array.filter((_, index) => index >= itemsToRemove)`: This method returns a new array containing all elements of the original array except those at the first `itemsToRemove` indices.
2. `array.map((_, index) => index >= itemsToRemove ? undefined : value)`: This method returns an empty array, as it will skip over the first `itemsToRemove` elements.

However, these alternatives may have different performance characteristics and use cases compared to the methods tested in this benchmark.

**Benchmark Result Analysis**

The latest benchmark result shows that:

1. `array.splice()` is the fastest method with an average execution speed of 7105294.5 executions per second.
2. `array.slice()` is slightly slower, with an average execution speed of 13915588.0 executions per second.
3. The custom `shift() + loop` approach is the slowest, with an average execution speed of 781259.0 executions per second.

Keep in mind that these results are specific to this benchmark and may vary depending on other factors such as array size, JavaScript engine version, and hardware configuration.

Related benchmarks:

Slice vs Splice vs Shift (100) (version: 0)

Compares the speed for removing 100 items from the beginning of an array

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

Created: one year ago by: Guest

Jump to the latest result

array.slice()

array.splice()

array.shift()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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