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

Script Preparation code:

var arr = [10];

Tests:

unshift
for (let i = 0; i < 50; i++){ arr.unshift(i); }
push + reverse
for (let i = 0; i < 50; 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

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
unshift	726.2 Ops/sec
push + reverse	2136.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring JavaScript performance is crucial in understanding how different libraries and techniques impact application speed. Let's break down the provided benchmark:

**What is being tested?**

The test compares two approaches to adding elements to an array and then reversing it: `unshift` vs `push + reverse`.

**Options compared:**

1. **Unshift**: Adds an element to the beginning of the array, shifting all existing elements one position forward.
2. **Push + Reverse**: Adds an element to the end of the array using the `push()` method and then reverses the entire array using the `reverse()` method.

**Pros and Cons:**

* **Unshift**:
	+ Pros: More efficient for adding elements at the beginning, as it avoids shifting all existing elements.
	+ Cons: Slower than `push + reverse` because it requires iterating over the entire array to add each element.
* **Push + Reverse**:
	+ Pros: Faster overall, since reversing only affects the last few elements added using `push()`.
	+ Cons: Requires two operations (adding and reversing), which can be slower than a single operation like `unshift`.

**Library/Library-less approaches:**

The test does not use any libraries. The code is self-contained in the JavaScript file.

**Special JS feature/syntax:**

There are no special JavaScript features or syntax used in this benchmark. It's straightforward, vanilla JavaScript.

**Other alternatives:**

If you were to modify this benchmark, you could consider adding other approaches, such as:

* Using `concat()` instead of `push()`
* Using a data structure like a linked list or array pool
* Using WebAssembly or native code for performance-critical operations
* Adding more complex scenarios, such as inserting elements at specific indices

Keep in mind that the optimal approach may vary depending on the specific use case and requirements.

**Benchmark preparation:**

The benchmark definition includes:

1. **Script Preparation Code**: A line of code to initialize an array `arr` with a single element.
2. **Html Preparation Code**: None, as the test only focuses on JavaScript performance.

The individual test cases are defined in separate objects, each containing:

1. **Benchmark Definition**: The actual code that performs the operation being tested (e.g., `unshift()` or `push() + reverse()`).
2. **Test Name**: A descriptive name for the benchmark case.

Related benchmarks:

arr unshift vs push + reverse (mid 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>

Fastest: N/A

Slowest: N/A

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