Benchmark: Replace with clean + push VS splice

Script Preparation code:

var list = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15];
var items = [16,17,18,19,20,21,22,23,24,25];

Tests:

clean+push
list.splice(0, list.length) list.push(items)
splice
list.splice(0, list.length, items)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
clean+push
splice

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/130.0.0.0 Safari/537.36

Browser/OS: Chrome 130 on Windows

View result in a separate tab

Test name	Executions per second
clean+push	1385169.0 Ops/sec
splice	1895390.4 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

### Benchmark Overview

The benchmark focuses on testing the performance of two distinct approaches to manipulate an array in JavaScript using the `splice()` method versus a combination of `splice()` and `push()`. The central question is which method performs better in terms of execution speed.

### Options Compared

1. **Option 1: clean + push**
   - **Benchmark Definition**: `list.splice(0, list.length); list.push(items);`
   - **Description**: This approach first clears the `list` array using `splice()`, effectively removing all its elements. Subsequently, it adds the elements of the `items` array to the end of `list` using the `push()` method.

2. **Option 2: splice**
   - **Benchmark Definition**: `list.splice(0, list.length, items);`
   - **Description**: This method also clears the contents of the `list` array but does so in a single operation by using `splice()` with the `items` array as an argument. This means it effectively replaces the entire content of the `list` in one action.

### Performance Results

The benchmark results from Chrome 130 on Windows show:
- **splice**: 1,895,390.375 Executions per Second
- **clean + push**: 1,385,169.0 Executions per Second

From these results, it is evident that the `splice` method, which combines clearing and pushing items in a single operation, outperforms the separate `clean + push` approach.

### Pros and Cons

#### clean + push
- **Pros**:
  - Clear separation of concerns: The array is first cleared, and then new items are added (could be easier to read for some).
  - Useful in scenarios where you need to clear an array and then conditionally add different items.
  
- **Cons**:
  - Generally slower based on benchmark results, as it involves two separate array operations (clear and push).
  
#### splice
- **Pros**:
  - More efficient in performance as it condenses the operations into one.
  - Simplifies code in the context of replacing an entire array's contents.

- **Cons**:
  - Slightly less intuitive to some developers who may not be familiar with how `splice()` can also add elements.
  
### Libraries and Special Features

No special libraries are used in this benchmark, nor is there any unique JavaScript feature being tested beyond standard array manipulation methods.

### Other Alternatives

1. **Array.prototype.length = 0**: Another common method to clear an array is simply setting its length to zero (e.g., `list.length = 0;`). This approach is often very fast and may, in some cases, outperform `splice()`. After zeroing the length, you can use `Array.prototype.push.apply()` to add multiple items all at once.

```javascript
   list.length = 0;
   Array.prototype.push.apply(list, items);
   ```

2. **Spread Operator**: If the context allows usage of modern JavaScript syntax, one can use the spread operator to create a new array altogether.

```javascript
   list = [...items];
   ```

This method does not modify the original array, thus, it might not suit scenarios where mutability is desired.

### Conclusion

The benchmark provides insightful performance comparisons between two common methods of array manipulation in JavaScript. The results clearly indicate that using `splice()` for both clearing and adding items is a more efficient approach. Depending on the specific use case and readability preferences, developers can choose among several methods for array manipulation, with the awareness that performance may vary based on the approach utilized.

Related benchmarks:

Replace with clean + push VS splice (version: 1)

Comparing performance of: clean+push vs splice

Created: one year ago by: Guest

Jump to the latest result

clean+push

splice

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):