Benchmark: slice vs splice for inserting object 1000

Script Preparation code:

var events = [];
var virtualEventIndex = 400
var virtualEvent = { key: 'virtual' }
for (var i = 0; i < 1000; i++) {
  events.push({ key: i });
}

Tests:

slice
var newEvents = [ ...events.slice(0, virtualEventIndex), virtualEvent, ...events.slice(virtualEventIndex), ]
splice
events.splice(virtualEventIndex, 0, virtualEvent)

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: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:73.0) Gecko/20100101 Firefox/73.0

Browser/OS: Firefox 73 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
slice	47162.3 Ops/sec
splice	823.5 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The provided benchmark compares two approaches for inserting an object into an array: using `slice` and using `splice`. The test case consists of creating an array of 1000 objects, removing a specific object from the middle (at index 400), and then re-inserting that object at the same position.

**Options Compared**

The benchmark compares two options:

1. **Using `slice`**: Specifically, the code uses `events.slice(0, virtualEventIndex)` to get the first part of the array up to the removed object's original index, `virtualEvent` to insert, and then `events.slice(virtualEventIndex)` to get the second part of the array from the removed object's new index. This creates a new array with the object inserted.
2. **Using `splice`**: The code uses `events.splice(virtualEventIndex, 0, virtualEvent)` to directly insert the object at the specified position.

**Pros and Cons**

* **Using `slice`**:
	+ Pros: Creates a shallow copy of the original array, which can be beneficial if you need to preserve the original array's state. The resulting array is also more predictable, as it doesn't modify the original array.
	+ Cons: Creates two new arrays (one for the first part and one for the second part), which can be memory-intensive.
* **Using `splice`**:
	+ Pros: Modifies the original array in place, reducing memory usage. It's also generally faster than creating multiple arrays.
	+ Cons: The original array is modified, which can have unexpected consequences if you need to preserve its state.

**Library and Syntax**

There are no libraries explicitly mentioned in the benchmark code. However, `slice` and `splice` are built-in JavaScript methods that operate on arrays.

No special JavaScript features or syntax are used in this benchmark.

**Other Considerations**

When choosing between these two approaches, consider the following factors:

* **Memory usage**: If memory efficiency is crucial, using `splice` might be a better choice.
* **Predictability and stability**: If you need to ensure that the resulting array doesn't modify the original array's state, using `slice` might be more suitable.
* **Performance**: Using `splice` can generally be faster than creating multiple arrays with `slice`.

**Other Alternatives**

If you're looking for alternative approaches to inserting objects into an array, consider:

* Using a library like `lodash` or `ramda`, which provide optimized and tested implementations of array operations.
* Using a different data structure, such as a linked list or a queue, if the above options don't meet your requirements.

Keep in mind that the best approach depends on your specific use case, performance requirements, and personal preferences.

Related benchmarks:

slice vs splice for inserting object 1000 (version: 0)

Comparing performance of: slice vs splice

Created: 4 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 one month ago):