Benchmark: Array splice vs object re assign

Script Preparation code:

var input = [];
for (var i = 0; i < 50000; i++) {
    input.push({
        id: i,
        data: 'something'
    })
}

Tests:

Array splice
const index = input.findIndex(val => val.id === 999); input.splice(index, 1);
Object re assign
var input = []; for (var i = 0; i < 49999; i++) { input.push({ id: i, data: 'something' }) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array splice
Object re assign

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.110 Safari/537.36

Browser/OS: Chrome 96 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array splice	1808.5 Ops/sec
Object re assign	1451.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the provided benchmark and explain what is tested, compared, pros and cons of different approaches, and other considerations.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark named "Array splice vs object re assign". This benchmark tests the performance difference between two approaches:

1. **Array Splice**: Using `splice()` method to remove an element from an array.
2. **Object Re Assign**: Creating a new array and assigning it to a variable, which effectively achieves the same result as removing an element from the original array.

**Benchmark Preparation Code**

The script preparation code for this benchmark creates an array with 50,000 elements, each containing `id` and `data` properties.
```javascript
var input = [];
for (var i = 0; i < 50000; i++) {
    input.push({
        id: i,
        data: 'something'
    });
}
```
**Individual Test Cases**

There are two test cases:

1. **Array Splice**: This test case uses the `splice()` method to find and remove an element from the array.
```javascript
const index = input.findIndex(val => val.id === 999);
input.splice(index, 1);
```
2. **Object Re Assign**: This test case creates a new array with 50,000 elements, which achieves the same result as removing an element from the original array.

**Pros and Cons of Different Approaches**

1. **Array Splice**:
	* Pros: Simple and straightforward.
	* Cons:
		+ Can be slow for large arrays due to the overhead of finding the index.
		+ May cause additional work when shifting elements after removal.
2. **Object Re Assign**:
	* Pros:
		+ Avoids the overhead of finding the index.
		+ Does not modify the original array.
	* Cons:
		+ Creates a new array, which can be memory-intensive for large arrays.
		+ May have performance implications if the new array is created frequently.

**Library Usage**

There is no explicit library usage in this benchmark. However, the `findIndex()` method used in the Array Splice test case is a part of the ECMAScript standard and is supported by most modern JavaScript engines.

**Special JS Features or Syntax**

The benchmark uses ES6 syntax features:

* `const` declaration for variable binding.
* Arrow functions (`=>`) for defining small anonymous functions.
* Template literals (`\r\n`) for creating multiline strings.

**Other Considerations**

When evaluating the performance of these two approaches, consider factors such as:

* Array size and complexity
* Memory constraints (e.g., if memory allocation or copying is costly)
* CPU instructions and architecture
* Cache locality and coherence

The benchmark results provided show that Chrome 96 on a Desktop platform has faster execution times for both test cases. However, the actual performance differences may vary depending on specific use cases and environments.

**Alternatives**

If you need to optimize array manipulation performance, consider the following alternatives:

1. **Use `map()` or `filter()`**: Instead of `splice()`, use these methods to create new arrays with modified elements.
2. **Use a library like Lodash**: Some libraries provide optimized implementations for array manipulation operations.
3. **Consider using a different data structure**: If performance is critical, consider switching to a different data structure, such as a linked list or a hash table.

Remember that the best approach depends on your specific use case and requirements. Always profile and benchmark your code to determine the most efficient solution.

Related benchmarks:

Array splice vs object re assign (version: 0)

Comparing performance of: Array splice vs Object re assign

Created: 3 years ago by: Guest

Jump to the latest result

Array splice

Object re assign

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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