Benchmark: splice vs unshift

Script Preparation code:

var arr = [1,2,3,4,5,6,7,8,9];

Tests:

splice
arr.splice(0,0,0);
unshift
arr.unshift(0);

Historical Performance Data aggregated from 5 community runs

Desktop Results:

Chrome 5 runs

unshift

24K/s

splice

24K/s

View exact numbers

✓ unshift: 24,299 ops/sec
• splice: 24,206 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

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: 11 months ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:142.0) Gecko/20100101 Firefox/142.0

Browser/OS: Firefox 142 on Ubuntu

View result in a separate tab

unshift

521K/s

splice

4K/s

View exact numbers

Test name	Executions per second
✓ unshift	520,879 Ops/sec
splice	4,398 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of MeasureThat.net and explore what's being tested in this benchmark.

**What is being tested?**

The provided JSON represents a benchmark that compares the performance of two approaches: using `splice` and `unshift` to prepend a value to an array. The test case uses JavaScript, specifically Array.prototype methods.

**Options compared**

There are only two options being compared:

1. **`arr.splice(0, 0, 0)`**: This method removes the first element from the array (up to the specified length) and replaces it with a new value.
2. **`arr.unshift(0)`**: This method inserts a new value at the beginning of the array.

**Pros and cons**

* `splice`: Pros:
	+ More flexible, as you can specify how many elements to remove and replace.
	+ Can be used to modify arrays in-place.
Cons:
	+ Generally slower than `unshift` because it has to search for the insertion point.
* `unshift`: Pros:
	+ Faster than `splice`, especially for small arrays or when inserting at the beginning.
Cons:
	+ Less flexible, as you're limited to adding a single element.
	+ Creates a new array and modifies the original.

**Other considerations**

The test case uses a sample array with 9 elements. The performance difference between these two methods is likely due to the overhead of searching for the insertion point in `splice` versus simply inserting at the beginning in `unshift`. However, this may not be significant for small arrays or when using `splice` for more complex modifications.

**Library**

There doesn't seem to be an external library being used in this benchmark. The test code is straightforward and only utilizes built-in JavaScript methods.

**Special JS feature or syntax**

This benchmark does not appear to use any special JavaScript features or syntax beyond the standard Array.prototype methods.

**Alternative approaches**

Other approaches that could be compared in this benchmark might include:

* Using `concat()` instead of `unshift`
* Using `slice()` and assignment to create a new array instead of modifying the original
* Using a different data structure, such as an object or a linked list, for the prepend operation

These alternatives would require modifications to the test code and may introduce additional complexity. The focus of MeasureThat.net is typically on comparing the performance of built-in JavaScript methods and primitives.

splice vs unshift (version: 0)

splice vs unshift to prepend value

Comparing performance of: `splice vs unshift`

Created: 6 years ago by: Registered User

Go to the latest result

splice

unshift

Historical Performance Data aggregated from 5 community runs

Desktop Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

splice vs unshift (version: 0)

splice vs unshift to prepend value

Comparing performance of: splice vs unshift

Created: 6 years ago by: Registered User

Go to the latest result

splice

unshift

Historical Performance Data aggregated from 5 community runs

Desktop Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `splice vs unshift`