Benchmark: JS Array Clearing 2

Script Preparation code:

var a = [];
for (var i=0; i < 1000000;i++){
  a.push("item"+i);
}

Tests:

Length = 0
a.length = 0;
Splice
a.splice(0, a.length-1);
Re-assign
a = []

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Length = 0
Splice
Re-assign

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36

Browser/OS: Chrome 133 on Windows

View result in a separate tab

Test name	Executions per second
Length = 0	27164878.0 Ops/sec
Splice	38335840.0 Ops/sec
Re-assign	7482026.5 Ops/sec

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

LLMs can make mistakes. Check important info.

The benchmark titled "JS Array Clearing 2" evaluates the performance of different methods for clearing an array in JavaScript. The provided JSON includes preparation code and definitions for three distinct test cases that measure how quickly each method executes. Let's dive into each of these approaches, consider their pros and cons, and explore the broader context of array manipulation.

### Test Cases Explained

1. **Test Case: Length = 0**
   - **Benchmark Definition**: `a.length = 0;`
   - **Description**: This method clears the array by setting its length property to zero.
   - **Pros**: 
     - Very fast and efficient because it directly modifies the array's length.
     - Does not create a new array; the original array reference remains unchanged, which can be advantageous if other references to the array exist.
   - **Cons**: 
     - Changes the state of the existing array, which might not be desired if other parts of the code expect to retain the original elements.

2. **Test Case: Splice**
   - **Benchmark Definition**: `a.splice(0, a.length - 1);`
   - **Description**: This method uses the `splice` function to remove all elements from the array starting from index 0.
   - **Pros**: 
     - It provides an explicit way to remove elements from an array, which can enhance readability, especially in complex manipulations.
     - Allows for easier modification of specific elements if needed in other use cases.
   - **Cons**:
     - Typically slower than modifying the length property because it involves shifting elements and re-indexing the array.
     - Creates additional overhead, as it deals with more involved operations in terms of memory and reference handling.

3. **Test Case: Re-assign**
   - **Benchmark Definition**: `a = [];`
   - **Description**: This method clears the array by re-assigning it to a new empty array.
   - **Pros**: 
     - Simple and straightforward, especially when a fresh array is needed.
     - Communicates the intent of clearing the array very clearly to anyone reading the code.
   - **Cons**:
     - This method creates a new array reference, which means any existing references to the original array will not update to the new empty array.
     - It may lead to memory overhead if not managed properly, especially if many references are involved.

### Performance Results

According to the latest benchmark results executed on Chrome 134:

- The **Splice** method executed **46,818,464 times per second**, making it the fastest option.
- The **Length = 0** method followed closely with **39,640,120 executions per second**.
- The **Re-assign** method was significantly slower at **12,290,815 executions per second**.

### Other Considerations

- **Memory Management**: The choice of array clearing method can have implications for memory usage in a JavaScript application. Opting for `a.length = 0` might be more memory efficient than re-assigning `a = []`, especially in scenarios involving closures or other references to the array.
- **Code Clarity**: While performance is a crucial aspect, clarity and maintainability of the code should also be considered. For example, developers might prefer `splice` for its expressiveness when working with complex data manipulations.
- **JavaScript Engine Optimization**: Different JavaScript engines may optimize these operations differently. The observed performance could vary across environments (e.g., Node.js, different web browsers).
- **Other Alternatives**: Alternatives to these methods could include using functional programming techniques like `filter` to create a new array with only desired elements, but this would not be efficient for the purpose of clearing an array. Other languages or libraries (like Lodash) also provide utility methods for array manipulations, but they often introduce their performance characteristics and overhead.

In conclusion, the choice between these methods depends on the specific context, desired performance, and the functional requirements of the program. The benchmark serves to highlight that while simpler operations may generally be faster, readability and memory considerations are just as important in a holistic software development view.

Related benchmarks:

JS Array Clearing 2 (version: 1)

Comparing performance of: Length = 0 vs Splice vs Re-assign

Created: one month ago by: Guest

Jump to the latest result

Length = 0

Splice

Re-assign

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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