Benchmark: Best practice empty an array

Script Preparation code:

var size = 100000;

var arr1 = [];
var arr2 = [];
var arr3 = [];
var arr4 = [];

for (var i = 0; i < size; i++){
  arr1.push(i);
  arr2.push(i);
  arr3.push(i);
  arr4.push(i);
}

Tests:

Just instantiate new array
arr1 = [];
Set length to zero
arr2.length = 0;
Splice
arr3.splice(0, arr3.length);
Pop all values
while(arr4.length > 0){ arr4.pop(); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Just instantiate new array
Set length to zero
Splice
Pop all values

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4758.102 Safari/537.36

Browser/OS: Chrome 98 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Just instantiate new array	10518977.0 Ops/sec
Set length to zero	8504364.0 Ops/sec
Splice	5913087.5 Ops/sec
Pop all values	14575297.0 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 world of JavaScript benchmarks.

**What is being tested?**

The provided JSON represents a set of benchmark tests for emptying an array in JavaScript, specifically for four different approaches:

1. Instantiating a new empty array (`arr1 = []`)
2. Setting the length to zero (`arr2.length = 0`)
3. Using `splice` method to remove all elements from the beginning of the array (`arr3.splice(0, arr3.length)`)
4. Popping all values from the end of the array using a while loop (`while(arr4.length > 0){ arr4.pop(); }`)

**Options compared**

The benchmark tests compare four different approaches to emptying an array:

1. **Instantiation**: Creating a new empty array with `arr1 = []`
2. **Length setting**: Setting the length of the existing array to zero with `arr2.length = 0`
3. **Splice method**: Using the `splice` method to remove all elements from the beginning of the array with `arr3.splice(0, arr3.length)`
4. **Popping loop**: Popping all values from the end of the array using a while loop with `while(arr4.length > 0){ arr4.pop(); }`

**Pros and cons of each approach**

Here's a brief analysis of the pros and cons of each approach:

1. **Instantiation**:
	* Pros: Simple, efficient, and creates a new object that doesn't modify the original array.
	* Cons: Can lead to memory allocation overhead if done repeatedly.
2. **Length setting**:
	* Pros: Quick, doesn't create a new object, and modifies the existing array.
	* Cons: May lead to issues with array indexing or other operations that rely on the length being zero.
3. **Splice method**:
	* Pros: Flexible, allows for specifying start and end indices, and can be used for more complex array manipulation.
	* Cons: Can be slower than instantiation or length setting due to the overhead of modifying the array.
4. **Popping loop**:
	* Pros: Simple and efficient, doesn't create a new object, and modifies the existing array.
	* Cons: May lead to issues with stack overflow if done repeatedly (assuming JavaScript's limit on recursion).

**Library usage**

In this benchmark, no libraries are explicitly mentioned. However, it's worth noting that some browsers may use internal libraries or optimizations that affect the performance of these operations.

**Special JS feature or syntax**

None of the provided benchmark scripts utilize any special JavaScript features or syntax beyond what is necessary for testing the array empting functionality.

**Alternatives**

If you're interested in exploring alternative approaches to emptying an array, some options include:

1. Using `fill` method: `arr.fill(undefined);`
2. Using `map` and `filter` methods: `arr.map(() => null).filter(() => true)`
3. Using a regex replacement with an empty string: `arr.replace(/[^x]/g, '')`

Keep in mind that these alternatives may have different performance characteristics or behavior depending on the specific use case.

I hope this explanation helps! Let me know if you have any further questions.

Related benchmarks:

Best practice empty an array (version: 0)

Based on question on http://stackoverflow.com/questions/1232040/how-do-i-empty-an-array-in-javascript

Comparing performance of: Just instantiate new array vs Set length to zero vs Splice vs Pop all values

Created: 2 years ago by: Guest

Jump to the latest result

Just instantiate new array

Set length to zero

Splice

Pop all values

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):