Benchmark: deleting array in Js

Tests:

Just instantiate new array
var size = 10000; var arr1 = []; for (var i = 0; i < size; i++){ arr1.push(i); } arr1 = [];
Set length to zero
var size = 10000; var arr2 = []; for (var i = 0; i < size; i++){ arr2.push(i); } arr2.length = 0;
Splice
var size = 10000; var arr3 = []; for (var i = 0; i < size; i++){ arr3.push(i); } arr3.splice(0, arr3.length);
Pop all values
var size = 10000; var arr4 = []; for (var i = 0; i < size; i++){ arr4.push(i); } while(arr4.length > 0){ arr4.pop(); }
delete
var size = 10000; var arr4 = []; for (var i = 0; i < size; i++){ arr4.push(i); } delete arr4;

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
delete

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/108.0.0.0 Safari/537.36

Browser/OS: Chrome 108 on Windows

View result in a separate tab

Test name	Executions per second
Just instantiate new array	29681.3 Ops/sec
Set length to zero	30712.7 Ops/sec
Splice	30216.2 Ops/sec
Pop all values	24784.1 Ops/sec
delete	34655.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**What is being tested?**

MeasureThat.net is testing the performance of deleting an array in JavaScript. The benchmark definition specifies four different approaches to delete an array:

1. Instantiating a new empty array
2. Setting the length of an existing array to zero
3. Using `splice(0, arr3.length)` to remove all elements from an array
4. Popping all values from an array using a while loop

**Options compared**

The benchmark compares the performance of these four approaches:

* **Just instantiate new array**: Creating a new empty array and assigning it to a variable.
* **Set length to zero**: Setting the length property of an existing array to zero.
* **Splice**: Using `splice(0, arr3.length)` to remove all elements from an array.
* **Pop all values**: Popping all values from an array using a while loop.

**Pros and Cons**

Here are some pros and cons for each approach:

1. **Just instantiate new array**
	* Pros: Simple and efficient way to create a new empty array.
	* Cons: Creates a new object every time, which can lead to memory allocation overhead.
2. **Set length to zero**
	* Pros: Only modifies the existing array, reducing memory allocation overhead.
	* Cons: Can be slower than other methods due to the need to update the array's internal length property.
3. **Splice**
	* Pros: Efficient way to remove all elements from an array by modifying the array's internal length property.
	* Cons: Requires a second argument (the count of elements to remove) and can lead to unexpected behavior if not used carefully.
4. **Pop all values**
	* Pros: Simple and efficient way to remove all elements from an array using a while loop.
	* Cons: Can be slower than other methods due to the need to iterate over the array's elements.

**Library usage**

None of the benchmark definitions explicitly use any external libraries, but the `splice` method uses the internal implementation details of JavaScript arrays.

**Special JS features or syntax**

The benchmark defines a special case for deleting an array using the `delete` operator (`"delete arr4;"`). This feature is not specific to modern browsers and may have different behavior in older versions of JavaScript.

**Other alternatives**

There are other ways to delete an array, such as:

* Using `Array.prototype.fill()` with a value of `undefined`: `arr3.fill(undefined)`
* Using `Array.prototype.map()` and then spreading the result: `[...arr3].map(() => undefined)`
* Using a library like Lodash's `tail` function

However, these alternatives are not part of the standard JavaScript specification and may not be supported by all browsers or environments.

Related benchmarks:

deleting array in Js (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 vs delete

Created: 2 years ago by: Guest

Jump to the latest result

Just instantiate new array

Set length to zero

Splice

Pop all values

delete

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):