Benchmark: slice vs splice: which one is fastest to extract all data from a long array

Script Preparation code:

var list = [];
for (let i = 0; i < 100*1000; i++) {
  list.push(i);
}

Tests:

slice
let a; for (let i = 0; i < 1000; i++) { a = list.slice(i*100,i*100+100); }
splice
let a; for (let i = 0; i < 1000; i++) { a = list.splice(0, 100); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
splice

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down what's being tested in the provided JSON benchmark:

**Benchmark Name:** `slice vs splice: which one is fastest to extract all data from a long array`

**Description:** The benchmark compares the performance of two approaches to extract 100 elements from a large array (`list`) using a for loop.

**Script Preparation Code:**
```javascript
var list = [];
for (let i = 0; i < 100*1000; i++) {
  list.push(i);
}
```
This code generates a long array `list` with 100,000 elements by pushing numbers from 0 to 999,999.

**Html Preparation Code:** None

The benchmark does not involve any HTML-related code or execution.

Now, let's analyze the two individual test cases:

1. **Test Case: "slice"**

```javascript
let a;
for (let i = 0; i < 1000; i++) {
  a = list.slice(i*100, i*100+100);
}
```
This code uses the `Array.prototype.slice()` method to extract 100 elements from the `list` array starting at index `i*100`. The variable `a` will hold the extracted slice.

2. **Test Case: "splice"**

```javascript
let a;
for (let i = 0; i < 1000; i++) {
  a = list.splice(0, 100);
}
```
This code uses the `Array.prototype.splice()` method to remove and return 100 elements from the beginning of the `list` array. The variable `a` will hold the removed slice.

**Options Compared:**

* **Slice**: Uses the `slice()` method to extract a contiguous subset of elements from the array.
* **Splice**: Uses the `splice()` method to remove and return a subset of elements from the beginning of the array.

**Pros and Cons:**

* **Slice**:
	+ Pros: More predictable performance, less overhead due to splicing the array (only removes elements, not reassigns the array's length).
	+ Cons: May not be as efficient if the slice is large or near the end of the array.
* **Splice**:
	+ Pros: Can remove and return multiple elements at once, which may be beneficial in certain scenarios.
	+ Cons: More overhead due to splicing the array (reassigns the array's length), which can impact performance.

**Library:** None

There are no external libraries used in these benchmark tests.

**Special JS Feature or Syntax:** None

The benchmark does not use any special JavaScript features or syntax that requires explanation.

**Other Alternatives:**

* Other methods to extract a slice from an array, such as `Array.prototype.subarray()` or using `Array.from()`, are not tested here.
* Alternative approaches, like using `Array.prototype.map()` or other functional programming techniques, are also not tested in this benchmark.

The benchmark results show that the "splice" method is faster than the "slice" method for this specific test case. However, please note that performance can vary depending on the specific use case and array characteristics.

Related benchmarks:

slice vs splice: which one is fastest to extract all data from a long array (version: 0)

100k list In a for loop, extract 100 positions from the array each iteration

Comparing performance of: slice vs splice

Created: 3 years ago by: Guest

Jump to the latest result

slice

splice

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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