Benchmark: .at vs length -1

Script Preparation code:

var array = Array.from({length: 100}).map(Math.random);

Tests:

array[array.length - 1]
var d = array[array.length - 1];
array.at(-1)
var z = array.at(-1);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
array[array.length - 1]
array.at(-1)

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 23 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Windows

View result in a separate tab

Test name	Executions per second
array[array.length - 1]	46202888.0 Ops/sec
array.at(-1)	48371060.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the explanation into smaller sections to make it easier to understand.

**Benchmark Definition**

The provided JSON represents a JavaScript benchmark, specifically testing two approaches: accessing an array element using the `at()` method versus accessing it directly with square bracket notation (`[]`).

**Options Compared**

Two options are being compared:

1. **Array.at()**: The `at()` method allows you to access an element in an array without having to specify its index. It's a more concise and expressive way of accessing elements.
2. **Square Bracket Notation ([])**: This is the traditional way of accessing an element in an array by specifying its index.

**Pros and Cons**

Here are some pros and cons of each approach:

* **Array.at()**:
	+ Pros: More concise, expressive, and readable code.
	+ Cons: May not be as widely supported across different browsers or environments (at least in older versions).
* **Square Bracket Notation ([])**:
	+ Pros: Wide support across browsers and environments, especially for older versions that don't support `at()`.
	+ Cons: Less concise and may look less readable.

**Library Usage**

There is no explicit library usage mentioned in the benchmark definition. However, it's worth noting that some browsers (e.g., Safari) have historically provided better performance for array access using the `at()` method compared to direct bracket notation.

**Special JavaScript Features/Syntax**

The benchmark uses a special feature called **Array.from()**, which is used to create an array from an iterable object. This syntax was introduced in ECMAScript 2015 (ES6).

Other considerations:

* The benchmark is designed to compare the performance of two approaches, making it useful for identifying potential bottlenecks or areas where optimization might be necessary.
* By using a large array and random values, the benchmark aims to create a realistic scenario that mimics real-world usage.

**Alternatives**

If you're looking for alternative benchmarks or test cases, here are some options:

1. **Benchmarking libraries**: Libraries like BenchmarkJS, Microbenchmark, or jsperf can help you write and compare benchmarks.
2. **Standardized benchmarks**: Organizations like the ECMAScript Committee provide standardized benchmarks for JavaScript features and performance.
3. **Browser-specific benchmarks**: Some browsers (e.g., Chrome) offer their own benchmarking tools or APIs that can be used to create custom benchmarks.

Keep in mind that each of these alternatives has its own strengths, weaknesses, and use cases.

Related benchmarks:

.at vs length -1 (version: 0)

Comparing performance of: array[array.length - 1] vs array.at(-1)

Created: one year ago by: Guest

Jump to the latest result

array[array.length - 1]

array.at(-1)

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):