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 gemma2:9b, generated one year ago):

LLMs can make mistakes. Check important info.

This benchmark compares the performance of two methods for removing the first element from an array in JavaScript:  `arr.shift()` and `arr.slice(1)`.

**Description:**

* **`arr.shift();`**: This method directly removes the first element from the array and returns it. It modifies the original array.
* **`arr.slice(1)`**: This method creates a new array containing all elements from the second element (index 1) to the end of the original array.  It does not modify the original array.

**Options Compared:**

* **Direct Removal vs. Creating a New Array:** The benchmark tests whether directly removing the first element (`shift()`) or creating a new array without the first element (`slice(1)`) is faster.

**Pros and Cons:**

* **`shift()`**:
    * **Pro:** Faster for removing the *first* element as it directly modifies the array, avoiding unnecessary array copying.
    * **Con:** Modifies the original array in place. If you need to keep the original array intact, `slice(1)` is a better option.

* **`slice(1)`**:
    * **Pro:**  Returns a *new* array, leaving the original array unchanged. Useful when you need multiple copies of the array with different modifications.
    * **Con:** Creates a new array copy, which can be slightly slower than `shift()` for removing only the first element because it involves copying data.

**Other Considerations:**

* **Array Size:** For very large arrays, the performance difference between `shift()` and `slice(1)` might become less significant.
* **Frequency of Operation:** If you frequently need to remove the first element from an array, `shift()` is likely more efficient due to its direct modification.

**Alternatives:**

* **`splice()`**:  A more versatile method that can remove elements at any index and add new elements. However, it might be slower than `shift()` for removing only the first element.

Let me know if you have any other questions.

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 gemma2:9b, generated one year ago):