Benchmark: splice vs = - MeasureThat.net

Script Preparation code:

var list = [];
for (var i = 0; i < 1000 * 1000; i++) {
  list.push(i);
}

Tests:

=
list = [];
splice
list.splice(0, list.length);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
=
splice

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what's being tested, the options being compared, their pros and cons, and other considerations.

**Benchmark Definition**

The benchmark definition represents two different ways to create an empty array in JavaScript: using the assignment operator (=) and the `splice` method.

```json
"Name": "splice vs =",
"Description": "100k list\nsplice and shift win, they mutate list\nslice loose, it creates a copy of list\n7.5x slower"
```

The description suggests that the `splice` method is generally faster than using the assignment operator for creating an empty array.

**Script Preparation Code**

This code initializes a large array (`list`) with 1 million elements.

```javascript
var list = [];
for (var i = 0; i < 1000 * 1000; i++) {
  list.push(i);
}
```

This preparation code is used to create a large array, which will be modified by the `splice` method in one test case and assigned using the assignment operator in the other.

**Options being compared**

Two options are being compared:

1. **Assignment Operator (=)**: This creates a new variable `list` and assigns it an empty value.
```javascript
var list = [];
```
Pros: simple, concise, and widely supported.

Cons: can lead to unexpected behavior if not used carefully (e.g., assigning values to existing variables).

2. **Splice Method (`splice`)**: This modifies the original array by removing elements starting from index 0 until the end of the array.
```javascript
list.splice(0, list.length);
```
Pros: can be efficient for arrays with a large number of empty slots.

Cons: modifies the original array, which might not be desirable in some scenarios; also, it's generally slower than using the assignment operator.

**Library and special features**

There is no explicit library mentioned in the benchmark definition. However, note that Chrome Edgion (not "Edg/92.0.902.73") uses a custom JavaScript engine that might have different behavior compared to other browsers or engines.

No special JavaScript features or syntax are being tested in this benchmark.

**Alternative approaches**

Other approaches to create an empty array include:

* Using `Array.from()` and passing an empty iterable: `var list = Array.from();`
* Using the `new` keyword with `Array`: `var list = new Array();`
* Using a function that returns an empty array: `function getEmptyList() { return []; } var list = getEmptyList();`

These alternatives are not being tested in this benchmark.

**Benchmark preparation code for individual test cases**

Two individual test cases are provided, each with its own script preparation code:

1. `=`
```javascript
var list = [];
for (var i = 0; i < 1000 * 1000; i++) {
  list.push(i);
}
```

2. `splice`
```javascript
list.splice(0, list.length);
```

These test cases are likely used to measure the performance of each approach in isolation.

**Latest benchmark result**

The latest benchmark results show that Chrome 92 (on a desktop platform) executes the assignment operator (`=`) approximately 7.5x faster than the `splice` method, which is consistent with the description provided in the benchmark definition.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.131 Safari/537.36 Edg/92.0.902.73

Browser/OS: Chrome 92 on Windows

View result in a separate tab

Test name	Executions per second
=	3489042.2 Ops/sec
splice	2173032.8 Ops/sec

Related benchmarks:

splice vs = (version: 0)

100k list splice and shift win, they mutate list slice loose, it creates a copy of list 7.5x slower

Comparing performance of: = vs splice

Created: 3 years ago by: Registered User

Jump to the latest result

=

splice

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):