Benchmark: truncating array: slice vs splice

Script Preparation code:

var list = [];
for (var i = 0; i < 1000000; i++) {
  list.push ({ timestamp: Math.round (+new Date() / 1000) });
}

Tests:

slice
var list2 = list.slice (0, 101)
splice
list.splice(101)

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:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.84 Safari/537.36

Browser/OS: Chrome 99 on Linux

View result in a separate tab

Test name	Executions per second
slice	5113900.0 Ops/sec
splice	7220007.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares two approaches for truncating an array in JavaScript: using `Array.prototype.slice()` versus `Array.prototype.splice()`. The test creates a large array of 1,000,000 objects and then attempts to slice or splice it at different points.

**Options Compared**

There are two options being compared:

1. **`slice()`**: This method returns a shallow copy of the original array, truncated to the specified length.
2. **`splice()`**: This method modifies the original array by removing elements from the end and returning an array of removed elements. In this case, we're trying to remove 101 elements.

**Pros and Cons**

* **`slice()`**:
	+ Pros: Fast, efficient, and doesn't modify the original array.
	+ Cons: Creates a new array object, which can be memory-intensive for large arrays.
* **`splice()`**:
	+ Pros: Modifies the original array in place, reducing memory usage.
	+ Cons: Slower than `slice()`, especially when dealing with large arrays.

**Library Used**

There is no specific library mentioned in this benchmark. Both `Array.prototype.slice()` and `Array.prototype.splice()` are built-in JavaScript methods.

**Special JS Feature/ Syntax**

None of the code uses any special JavaScript features or syntax that's not widely supported.

**Other Alternatives**

If you were to optimize your array truncation using a different approach, some alternatives could be:

* Using `Array.prototype.filter()` to create a new array with only the desired elements.
* Using `Array.prototype.reduce()` and slicing the resulting array.
* Implementing a custom, optimized algorithm for array truncation.

However, it's worth noting that these alternatives might not be as straightforward or efficient as using `slice()` or `splice()`, depending on the specific use case and performance requirements.

In summary, this benchmark is testing the performance of two common JavaScript methods for array truncation: `Array.prototype.slice()` and `Array.prototype.splice()`.

Related benchmarks:

truncating array: slice vs splice (version: 0)

Comparing performance of: slice vs splice

Created: 2 years ago by: Guest

Jump to the latest result

slice

splice

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):