Benchmark: arr unshift vs push + reverse (small array) one item

Script Preparation code:

var arr = [1,2,3,4,5];

Tests:

unshift
arr.unshift(6);
push + reverse
arr.reverse(); arr.push(6); 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: 5 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36 OPR/126.0.0.0

Browser/OS: Opera 126 on Linux

View result in a separate tab

Test name	Executions per second
unshift	46265.7 Ops/sec
push + reverse	1273.2 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided JSON benchmark definition and test cases to explain what's being tested, the options compared, pros and cons of each approach, and other considerations.

**Benchmark Definition**

The benchmark definition is a JSON object that describes the test case:

* `Name`: A unique name for the benchmark.
* `Description`: An optional description of the benchmark. In this case, it's empty.
* `Script Preparation Code`: The code that sets up the test environment before running the actual benchmark. This includes declaring an array variable `arr` with 5 elements: `[1,2,3,4,5]`.
* `Html Preparation Code`: An optional code that prepares the HTML for the benchmark. In this case, it's empty.

**Individual Test Cases**

There are two test cases defined in the JSON:

1. **unshift**
	* Benchmark Definition: `arr.unshift(6);`
This test case creates an array with 5 elements `[1,2,3,4,5]` and then uses the `unshift()` method to add the element `6` at the beginning of the array.
2. **push + reverse**
	* Benchmark Definition: `arr.reverse();\r\narr.push(6);\r\narr.reverse();`
This test case creates an array with 5 elements `[1,2,3,4,5]`, reverses it using `reverse()`, pushes the element `6` onto the end of the reversed array, and then reverses it again.

**Options Compared**

In this benchmark, two approaches are being compared:

1. **unshift**: This method adds an element to the beginning of the array.
2. **push + reverse**: This approach involves pushing an element onto the end of the array and then reversing it.

**Pros and Cons of Each Approach**

Here's a brief overview of the pros and cons of each approach:

* **unshift**:
	+ Pros: Can be more efficient than `push + reverse` for certain data structures or use cases.
	+ Cons: May have performance issues when dealing with large arrays, as it requires shifting all existing elements to make space for the new one.
* **push + reverse**:
	+ Pros: More flexible and can be used in scenarios where `unshift()` is not suitable (e.g., when adding elements to the end of an array).
	+ Cons: May have slower performance than `unshift` due to the extra step of reversing the array.

**Library Use**

In both test cases, a library is being used implicitly by JavaScript:

* The `Array.prototype.unshift()` and `Array.prototype.reverse()` methods are part of the standard JavaScript API.
* No explicit libraries are mentioned in the benchmark definition or individual test cases.

**Special JS Feature/Syntax**

There's one special syntax to note:

* `\r\n` is a carriage return newline sequence, used in some platforms (like Windows) to indicate line breaks. In this case, it seems like a formatting issue; the `reverse()` and `push()` methods should work correctly regardless of this character.

**Other Alternatives**

Some alternative approaches could be considered:

* Using `concat()` instead of `push + reverse`: This would involve pushing an element onto the end of the original array using `concat()`, which might have different performance characteristics.
* Using a custom data structure or implementation: Depending on the specific requirements, alternatives like using a linked list, a binary search tree, or a custom stack data structure might offer better performance for certain use cases.

Keep in mind that these alternatives would require significant changes to the benchmark definition and individual test cases.

Related benchmarks:

arr unshift vs push + reverse (small array) one item (version: 0)

Comparing performance of: unshift vs push + reverse

Created: 3 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):