Benchmark: splice twice VS shift + pop 5k

Script Preparation code:

var list = [];
for (var i = 0; i < 500; i++) {
  list.push(i);
}

Tests:

splice twice
list = list.splice(1, 1); list = list.splice(list.length - 1, 1)
shift + pop
list.shift(); list.pop();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
splice twice
shift + pop

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks and explore what's being tested in this benchmark.

**Benchmark Definition**

The benchmark definition json represents a single test case. It has several important fields:

*   **Name**: A unique name for the benchmark, which can be used to identify it later.
*   **Description**: A brief description of the benchmark, providing context about what is being measured.
*   **Script Preparation Code**: A JavaScript code snippet that initializes a list and populates it with numbers from 0 to 499. This is done before each test case execution.
*   **Html Preparation Code**: An empty string, indicating that no additional HTML code needs to be generated for this benchmark.

**Individual Test Cases**

The benchmark definition also includes an array of individual test cases:

1.  **splice twice**: Measures the performance of removing two elements from a list using `list.splice(1, 1)` and then removing another element at the end of the list (`list.splice(list.length - 1, 1)`).
2.  **shift + pop**: Compares the performance of removing an element from both ends of a list simultaneously using `list.shift()` followed by `list.pop()`.

**Approaches Compared**

The benchmark is testing two different approaches for removing elements from a list:

*   **splice twice**: Uses `list.splice(1, 1)` to remove one element and then `list.splice(list.length - 1, 1)` to remove another element. This approach can lead to some overhead due to the repeated calls to `splice`.
*   **shift + pop**: Removes an element from both ends of the list simultaneously using `list.shift()` followed by `list.pop()`. This approach is generally more efficient because it only requires a single call to `length` and two calls to `pop`.

**Pros and Cons**

Here's a brief overview of each approach:

*   **splice twice**: Pros: Simple and easy to understand. Cons: More overhead due to repeated calls to `splice`.
*   **shift + pop**: Pros: More efficient, as it only requires a single call to `length` and two calls to `pop`. Cons: May be less intuitive for developers who are not familiar with this approach.

**Library Usage**

In this benchmark, no JavaScript libraries are explicitly mentioned. However, the test cases assume that the `list` variable is already initialized and populated with numbers from 0 to 499.

**Special JS Features or Syntax**

The benchmark does not use any special JavaScript features or syntax beyond what's typically used in everyday coding. It simply focuses on measuring the performance of list manipulation operations.

**Alternative Approaches**

Other alternatives for removing elements from a list include:

*   **forEach() + unshift()**: Removes an element and then adds it to the beginning of the list using `list.forEach((element) => { ... })` followed by `list.unshift(element)`.
*   **map() + push()**: Removes an element and then adds it to the end of the list using `list.map((_, index) => { if (index === 0) return undefined; return element; })` followed by `list.push(element)`.

Keep in mind that these alternative approaches might have different performance characteristics compared to `splice twice` or `shift + pop`.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36

Browser/OS: Chrome 75 on Windows

View result in a separate tab

Test name	Executions per second
splice twice	1699818.6 Ops/sec
shift + pop	5773704.5 Ops/sec

Related benchmarks:

splice twice VS shift + pop 5k (version: 0)

5k list

Comparing performance of: splice twice vs shift + pop

Created: 5 years ago by: Guest

Jump to the latest result

splice twice

shift + pop

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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