Benchmark: Array splice VS Array unshift

Tests:

Splice
let arr = [{ name: 'bob', lastname: 'bob' }, { name: 'bib', lastname: 'bib' }] arr.splice(0,0, { name: 'boub', lastname: 'boub' })
unshift
let arr = [{ name: 'bob', lastname: 'bob' }, { name: 'bib', lastname: 'bib' }]; arr.unshift({ name: 'boub', lastname: 'boub' })

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Splice
unshift

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/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Windows

View result in a separate tab

Test name	Executions per second
Splice	17814478.0 Ops/sec
unshift	15072557.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The MeasureThat.net website provides a platform for users to create and run JavaScript microbenchmarks. The benchmark in question compares the performance of two approaches: using `Array.splice()` versus using `Array.unshift()`. These methods are commonly used for inserting or removing elements from an array.

**Comparison Options**

There are two options being compared:

1. **Array.splice()**: This method modifies the original array by removing and replacing a specified number of elements, starting at the beginning of the array. In this benchmark, `arr.splice(0, 0, { name: 'boub', lastname: 'boub' })` is used to insert an element at the beginning of the array.
2. **Array.unshift()**: This method modifies the original array by adding one or more elements to the beginning of the array. In this benchmark, `arr.unshift({ name: 'boub', lastname: 'boub' })` is used to add an element at the beginning of the array.

**Pros and Cons**

Here are some pros and cons of each approach:

* **Array.splice()**:
	+ Pros:
		- Can be used to remove elements from the array.
		- Can be more efficient when dealing with large arrays, as it only needs to update the indices of the remaining elements.
	+ Cons:
		- Requires the number of elements to be removed, which can be inconvenient for dynamic cases.
		- May have performance implications if the array is very large or if the method is called frequently.
* **Array.unshift()**:
	+ Pros:
		- Allows for dynamic insertion without specifying a length.
		- Can be more convenient when dealing with small arrays or when inserting elements multiple times.
	+ Cons:
		- Creates a new copy of the array, which can lead to memory allocation overhead.
		- May have performance implications if called frequently on large arrays.

**Library and Special JS Features**

Neither `Array.splice()` nor `Array.unshift()` rely on specific libraries or special JavaScript features. However, it's worth noting that modern JavaScript engines may use optimizations for these methods, such as using native code or caching results.

**Other Alternatives**

Other alternatives to `Array.splice()` and `Array.unshift()` include:

* **Array.prototype.push()`: Adds an element to the end of the array.
* **Array.prototype.insert()`: Not a standard method in JavaScript, but some libraries and frameworks may provide this method as an extension.
* **Data structures like linked lists or stacks**: Can be used instead of arrays for efficient insertion and removal.

**Benchmark Results**

The provided benchmark results show that Chrome 120 on Desktop Windows achieved:

* **Array.splice()**: 17814478.0 executions per second
* **Array.unshift()**: 15072557.0 executions per second

This suggests that `Array.splice()` is currently the faster approach in this specific test case, but it's essential to note that these results may vary depending on the specific use case and implementation details.

In conclusion, understanding the differences between `Array.splice()` and `Array.unshift()`, as well as considering their pros and cons, can help developers make informed decisions when working with arrays in JavaScript.

Related benchmarks:

Array splice VS Array unshift (version: 0)

Comparing performance of: Splice vs unshift

Created: 2 years ago by: Guest

Jump to the latest result

Splice

unshift

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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