Benchmark: Array add vs .unshift()

Script Preparation code:

var arr = [1,2,3,4]

Tests:

.unshift()
arr.unshift(42)
add
[42] + arr

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
.unshift()
add

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:120.0) Gecko/20100101 Firefox/120.0

Browser/OS: Firefox 120 on Linux

View result in a separate tab

Test name	Executions per second
.unshift()	535278.0 Ops/sec
add	24.9 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 definition and test cases.

**Benchmark Definition**

The benchmark is called "Array add vs .unshift()" and it tests two different approaches to adding an element to the end of an array: using the `unshift()` method and a simple concatenation operation (`[42] + arr`).

**Script Preparation Code**
```javascript
var arr = [1,2,3,4];
```
This code initializes a sample array with four elements.

**Html Preparation Code**
Since there is no HTML preparation code provided, we can assume that the benchmark will run in a headless environment or a browser's console.

**Test Cases**

There are two individual test cases:

1. **".unshift()"**

This test case uses the `unshift()` method to add an element (42) to the beginning of the array (`arr.unshift(42)`).

2. **"add" (simple concatenation)**

This test case uses a simple concatenation operation (`[42] + arr`) to create a new array with the original elements and the added element.

**Library Used**

None, as this benchmark only uses built-in JavaScript features and no external libraries.

**Special JS Feature or Syntax**

The `unshift()` method is a special method in JavaScript that modifies an array by inserting one or more elements at the beginning of the array. The test case uses this feature to add an element to the beginning of the array.

In contrast, the simple concatenation operation (`[42] + arr`) uses the `+` operator, which creates a new array by concatenating the two operands.

**Pros and Cons**

**.unshift() method:**

Pros:

* Efficient for adding elements to the beginning of an array
* Native JavaScript method

Cons:

* Can be slower than simple concatenation for large arrays due to the overhead of creating a new array with a `push` or `splice` operation
* May have varying performance depending on the browser and engine used

**Simple Concatenation ( `[42] + arr` ):**

Pros:

* Efficient for small arrays or when adding elements at the beginning is not necessary
* Can be faster than using `unshift()` for large arrays due to the overhead of modifying an existing array

Cons:

* Creates a new array, which can lead to memory allocation and deallocation issues
* May have varying performance depending on the browser and engine used

**Other Considerations**

The benchmark results will provide insight into how different browsers and engines perform when using these two approaches.

In general, for small arrays or when adding elements at the beginning is not necessary, simple concatenation may be a faster option. However, for larger arrays or when modifying an existing array is desired, the `unshift()` method may be more efficient.

**Other Alternatives**

If you want to test alternative approaches, such as using `push()` instead of `unshift()`, or experimenting with different array lengths and data types, you can modify the benchmark definition and script preparation code accordingly.

Related benchmarks:

Array add vs .unshift() (version: 0)

Comparing performance of: .unshift() vs add

Created: one year ago by: Guest

Jump to the latest result

.unshift()

add

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):