Benchmark: JS Slice vs. Pop for last element

Script Preparation code:

var x = [1,2,3]

Tests:

slice
x.slice(-1)[0]
pop
x.pop()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
pop

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36

Browser/OS: Chrome 134 on Windows

View result in a separate tab

Test name	Executions per second
slice	31915342.0 Ops/sec
pop	96311640.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the explanation into smaller parts to make it easier to understand.

**Benchmark Description**

The provided JSON represents a JavaScript benchmark that compares two approaches for accessing the last element of an array: `x.slice(-1)[0]` and `x.pop()`. The benchmark is designed to test which approach is faster.

**Options Compared**

There are two options being compared:

1. **`x.slice(-1)[0]`**: This method creates a new array containing only the last element of the original array `x`, and then extracts that single element using indexing (`[0]`). The `-1` index tells `slice()` to start from the end of the array.
2. **`x.pop()`**: This method removes the last element from the array `x` and returns its value.

**Pros and Cons**

*   **`x.slice(-1)[0]`**:
    *   Pros: More explicit, easier to understand, and allows for additional processing of the sliced elements if needed.
    *   Cons: Creates a new array and can be slower due to the overhead of creating a new object.
*   **`x.pop()`**:
    *   Pros: Faster because it modifies the original array directly, which reduces the number of memory allocations and assignments required.
    *   Cons: Less explicit, and its use is more limited since it removes the last element from the array.

**Library Usage**

None of the test cases use any libraries explicitly. However, `slice()` and `pop()` are built-in methods provided by JavaScript, so they can be considered part of the language itself.

**Special JS Features or Syntax**

Neither of the options used in this benchmark leverages any special JavaScript features or syntax beyond the basic array manipulation methods (`slice()`, `pop()`, etc.). If it did, it would likely require a deeper analysis to understand the specifics.

**Other Alternatives**

If you wanted to compare other approaches for accessing the last element of an array, some alternatives could include:

*   Using `Array.prototype.at()` (which was introduced in ECMAScript 2019): This method is similar to `slice(-1)[0]` but provides more flexibility and safety features.
*   Using a library like Lodash's `last()` function: This would add an external dependency, which some might prefer or avoid depending on their project requirements.

These alternatives are not explicitly part of the benchmark provided in this JSON snippet.

Related benchmarks:

JS Slice vs. Pop for last element (version: 0)

Comparing performance of: slice vs pop

Created: 4 years ago by: Guest

Jump to the latest result

slice

pop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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