Benchmark: shift vs slice 1 element

Script Preparation code:

var arr = Array.from({ length: 120000 }, (_, i) => i)

Tests:

shift
arr.shift();
slice
arr.slice(1)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
shift
slice

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:140.0) Gecko/20100101 Firefox/140.0

Browser/OS: Firefox 140 on Linux

View result in a separate tab

Test name	Executions per second
shift	53557240.0 Ops/sec
slice	23103616.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the benchmark.

**Benchmark Description**

The benchmark tests the performance of two JavaScript methods: `arr.shift()` and `arr.slice(1)`, where `arr` is an array of 120,000 elements.

**Test Cases**

There are two test cases:

1. **Shift**: `arr.shift();`
	* This method removes the first element from the array.
2. **Slice**: `arr.slice(1)`
	* This method creates a new array that includes all elements except the first one (at index 0).

**Library and Features**

None of the test cases use any external libraries or special JavaScript features.

**What's Being Compared**

The benchmark compares two methods to remove or access the first element in an array:

1. **`arr.shift()`**: Removes the first element from the array.
2. **`arr.slice(1)`**: Creates a new array with all elements except the first one.

**Pros and Cons of Each Approach**

* `arr.shift()`:
	+ Pros: Fast, efficient, removes the first element directly.
	+ Cons: Modifies the original array.
* `arr.slice(1)`:
	+ Pros: Preserves the original array (no modification).
	+ Cons: Creates a new array, which can be slower and more memory-intensive.

**Other Considerations**

When deciding between these approaches, consider:

* **Performance**: If you need to remove the first element frequently, `arr.shift()` might be faster.
* **Preservation of Original Data**: If you want to keep the original array intact, use `arr.slice(1)`.
* **Array Size**: For very large arrays, `arr.slice(1)` might be more memory-efficient.

**Alternatives**

Other alternatives for removing or accessing the first element in an array include:

* Using a loop to iterate over the elements and remove the first one.
* Using a recursive function to remove the first element.
* Using a library like Lodash (e.g., `_.head()`) to access or remove the first element.

However, these alternatives might be less efficient than using built-in methods like `arr.shift()` or `arr.slice(1)`.

Related benchmarks:

shift vs slice 1 element (version: 0)

shift vs slice 1 element

Comparing performance of: shift vs slice

Created: 2 years ago by: Guest

Jump to the latest result

shift

slice

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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