Benchmark: arr unshift vs push + reverse (medium array)

Script Preparation code:

var count = 600;

Tests:

unshift
var arr = []; for (let i = 0; i < count; i++){ arr.unshift(i); }
push + reverse
var arr = []; for (let i = 0; i < count; i++){ arr.push(i); } arr.reverse();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
unshift
push + reverse

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark compares two approaches for adding elements to an array and then reversing it: `arr.unshift(i)` vs `arr.push(i) + arr.reverse()`. The test is designed to measure the performance of these approaches on a medium-sized array.

**Options Compared**

Two options are compared:

1. **`arr.unshift(i)`**: This approach adds an element to the beginning of the array using the `unshift()` method.
2. **`arr.push(i) + arr.reverse()`**: This approach adds an element to the end of the array using the `push()` method and then reverses the array.

**Pros and Cons of Each Approach**

1. **`arr.unshift(i)`**:
	* Pros: Less memory allocation and copying required, as it only adds one element at a time.
	* Cons: Slower for large arrays because `unshift()` needs to shift all existing elements to make room for the new one.
2. **`arr.push(i) + arr.reverse()`**:
	* Pros: Faster for large arrays because `push()` and `reverse()` are optimized to handle larger arrays with less overhead.
	* Cons: More memory allocation and copying required, as it creates a temporary array before reversing it.

**Library Usage**

None of the test cases use any external libraries. The benchmark focuses on measuring the performance of built-in JavaScript methods.

**Special JS Feature/Syntax**

The test case uses:

1. **`let i = 0;`**: A variable declaration using the `let` keyword, which is a modern JavaScript feature introduced in ECMAScript 2015 (ES6).
2. **`var count = 600;`**: A variable declaration using the `var` keyword, which is an older syntax that was widely used before ES6.

**Alternative Approaches**

Other approaches to add elements to an array and reverse it could include:

1. **Using `Array.prototype.shift()`**: Similar to `unshift()`, but shifts from the end of the array instead of the beginning.
2. **Using `Array.prototype.splice()`**: Replaces or removes elements at a specified position in the array, which can be more efficient than `push()` and `reverse()`.
3. **Using an external library like Lodash**: Provides optimized implementations for common array operations.

Keep in mind that the best approach depends on the specific use case and requirements of your application.

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/98.0.4758.81 Safari/537.36

Browser/OS: Chrome 98 on Windows

View result in a separate tab

Test name	Executions per second
unshift	12272.1 Ops/sec
push + reverse	24781.7 Ops/sec

Related benchmarks:

arr unshift vs push + reverse (medium array) (version: 0)

Comparing performance of: unshift vs push + reverse

Created: 2 years ago by: Guest

Jump to the latest result

unshift

push + reverse

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):