Benchmark: Pop vs length -1 vs at -1

Script Preparation code:

var array = [];

for(var i = 0; i < 100000; i++){array.push(Math.random());}

Tests:

pop
array.pop();
length - 1
array[array.length - 1];
at(-1)
array.at(-1);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
pop
length - 1
at(-1)

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

I'd be happy to help you understand the JavaScript microbenchmark on MeasureThat.net.

**Overview of the Benchmark**

The benchmark measures the performance of three different ways to access the last element in an array: `pop()`, `length - 1`, and `at(-1)`. The goal is to determine which approach is the fastest.

**Options Compared**

The three options compared are:

1. **`array.pop()`**: This method removes and returns the last element of the array.
2. **`array[length - 1]`**: This method accesses the last element of the array using an indexed syntax.
3. **`array.at(-1)`**: This method accesses the last element of the array, similar to `length - 1`, but it is a more modern and efficient way of accessing elements in arrays.

**Pros and Cons**

Here's a brief summary of each approach:

* **`array.pop()`**:
	+ Pros: Simple and widely supported.
	+ Cons: May have a higher performance overhead due to the removal operation, which can lead to shifting all elements after the removed element.
* **`array[length - 1]`**:
	+ Pros: Fast and efficient, with a low memory overhead.
	+ Cons: May not be as readable or intuitive for developers familiar with array indexing.
* **`array.at(-1)`**:
	+ Pros: Modern, efficient, and convenient way of accessing elements in arrays.
	+ Cons: Requires support for the `at()` method, which may not be available in older browsers.

**Library Used**

None is explicitly mentioned in the benchmark definition. However, the use of modern JavaScript features like `at()`, `length - 1`, and `pop()` suggests that the test is designed to work with a relatively recent version of JavaScript ( likely ECMAScript 2017 or later).

**Special JS Feature or Syntax**

The `at()` method is a modern JavaScript feature introduced in ECMAScript 2019. It allows accessing elements in arrays using an object-like syntax, which can be more convenient and expressive than traditional indexing.

**Other Considerations**

When writing benchmarks like this one, it's essential to consider factors like:

* Cache locality: Accessing elements in an array with a small index offset (like -1) is often faster due to cache locality.
* Memory allocation and deallocation overheads: Methods like `pop()` incur additional overheads due to the removal and re-insertion of elements.
* Syntax and readability: While performance matters, code readability and maintainability are also important.

**Alternatives**

If you're interested in exploring alternative benchmarking tools or approaches, some popular options include:

* jsbench.js
* BenchmarkJS
* V8 Microbenchmark Suite (for Node.js)
* Google's Performance Metrics (for web applications)

These tools offer various features and focus areas, such as code execution time measurement, memory profiling, or specific domain-specific benchmarks.

Please let me know if you'd like further clarification on any of these points!

Related benchmarks:

Pop vs length -1 vs at -1 (version: 0)

Comparing performance of: pop vs length - 1 vs at(-1)

Created: 3 years ago by: Guest

Jump to the latest result

pop

length - 1

at(-1)

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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