Benchmark: array.splice vs for loop with 2 arrays

Script Preparation code:


a = Array(10000);
b = Array(300)

Tests:

array.splice
a.splice(0, b.length, ...b);
for loop
for (let i = 0; i < b.length; i++) { a[i] = b[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
array.splice
for loop

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
array.splice	667386.0 Ops/sec
for loop	425431.5 Ops/sec

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

LLMs can make mistakes. Check important info.

### Benchmark Overview

The benchmark being assessed compares two different methods of populating an array in JavaScript:

1. Using the `splice` method.
2. Using a traditional `for` loop.

Both methods are tested within the context of modifying an array `a` with the elements from another array `b`.

### Benchmark Preparation Code

```javascript
a = Array(10000);
b = Array(300);
```

- **`a`**: An array is initialized with a length of 10,000. Initially, this array is empty but will be populated with the contents from array `b`.
- **`b`**: An array is initialized with a length of 300, which is the number of elements we want to insert into `a`.

### Test Cases

1. **`array.splice` Method**:
    - **Definition**: `a.splice(0, b.length, ...b);`
    - **Operation**: The `splice` method is called on the array `a` to remove elements starting from index `0` and replace them with elements spread from array `b`.
    
    **Pros**:
    - `splice` is a standard method for adding/removing elements without needing a loop, which can lead to cleaner, more readable code.
    - It modifies the array `a` in place.

**Cons**:
    - `splice` can be less performant for larger arrays as it may involve internal shifting of array elements and can carry function-call overhead.
    
2. **`for loop` Method**:
    - **Definition**:
    ```javascript
    for (let i = 0; i < b.length; i++) {
        a[i] = b[i];
    }
    ```
    - **Operation**: A `for` loop iterates over each element in array `b`, directly assigning its values to the first part of array `a`.
    
    **Pros**:
    - Typically faster because it involves direct assignment with less overhead compared to a higher-level function like `splice`.
    - More control over process, allowing for potential optimizations (e.g., modifying assignments).
    
    **Cons**:
    - More verbose and can lead to less readable code, especially if including additional logic inside the loop.

### Benchmark Results

The benchmark results show the number of executed operations per second for each method:

- **`array.splice`**: 643,831.5 executions per second.
- **`for loop`**: 416,554.59375 executions per second.

### Conclusion & Considerations

The benchmark indicates that the `splice` method outperforms the `for` loop in this particular scenario. However, it's essential to consider the context where each method will be used.

**Other Alternatives**:
- **Array Methods**: Other array manipulation methods such as `concat()`, `map()`, or using the spread operator in different contexts can also be alternatives.
- **Optimized Libraries**: Utilize libraries like Lodash or Underscore.js, which often provide utility functions that may optimize performance or enhance readability.
- **Typed Arrays**: In scenarios demanding high performance (like when handling numerical calculations), JavaScript Typed Arrays (like `Uint8Array`) could be considered, though they come with different use-cases and intricacies.

Ultimately, when choosing a method, one should consider readability, maintainability, and performance based on the specific requirements of the application being developed.

Related benchmarks:

array.splice vs for loop with 2 arrays (version: 1)

Comparing performance of: array.splice vs for loop

Created: one year ago by: Guest

Jump to the latest result

array.splice

for loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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