Benchmark: .at vs bracket notation

Script Preparation code:

let f;

Tests:

.at
for (let i = 30000; --i;) f=[1,2,3].at(3)
bracket
for (let i = 30000; --i;) f=[1,2,3][2]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
.at
bracket

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:144.0) Gecko/20100101 Firefox/144.0

Browser/OS: Firefox 144 on Windows

View result in a separate tab

Test name	Executions per second
.at	20598.3 Ops/sec
bracket	19092.1 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

### Benchmark Overview

This benchmark compares two different methods of accessing array elements in JavaScript: the `.at()` method and the traditional bracket notation (`[]`). It serves to evaluate the performance differences between these two approaches within an array containing numeric values.

### Options Compared

1. **.at() Method**
   - **Syntax:** `array.at(index)`
   - **Purpose:** The `.at()` method allows you to access elements at a specified index in an array while supporting negative integers, which count back from the last item in the array. For example, `array.at(-1)` gives you the last element.

2. **Bracket Notation**
   - **Syntax:** `array[index]`
   - **Purpose:** This is the traditional way of accessing elements in an array by specifying their index. It does not support negative indices, meaning you must specify a valid positive index concerning the array's length.

### Performance Analysis

The benchmark results show the number of executions per second for both methods when used in a loop:

- **Bracket Notation:**
  - **Executions Per Second:** 477.29
  - **Test Name:** "bracket"

- **.at() Method:**
  - **Executions Per Second:** 468.77
  - **Test Name:** ".at"

#### Pros and Cons

**.at() Method:**
- **Pros:**
  - Supports negative indexing, making it more convenient for certain use cases, such as accessing elements from the end of the array.
  - Provides clearer intent when reading the code, as it highlights that the method is specifically for indexing.

- **Cons:**
  - Slightly slower in this benchmark, which could indicate a performance overhead due to the method call.
  - May not be supported in older environments or versions of JavaScript that do not support ES2022, limiting compatibility.

**Bracket Notation:**
- **Pros:**
  - More universally recognized and widely used, so many developers may be more comfortable with it.
  - Often faster in terms of pure performance due to the direct access without function overhead.
  - Fully supported in all versions of JavaScript.

- **Cons:**
  - Lacks the convenience of negative indices.
  - Less immediately clear in terms of design since bracket notation does not indicate that it’s accessing an element (though this is often understood).

### Other Considerations

- **Readability and Maintainability:** When choosing between the two, consider the readability of the code. If you're working extensively with negative indices, `.at()` may be a more descriptive choice.

- **Compatibility:** Consider the environments where your code will run. If you're writing code meant to be used in various contexts or older browsers, bracket notation will likely be the safer choice.

### Alternatives

Besides `.at()` and bracket notation, other alternatives for array access include:

- **Array Destructuring:** This ES6 feature allows for a concise way to assign values from arrays to variables. However, it's not direct indexing.
  
  ```javascript
  const [first, second] = [1, 2, 3]; // Accessing first and second elements
  ```

- **Using Higher-Order Functions:** Functions like `.map()`, `.filter()`, and `.reduce()` allow you to work with arrays in a more functional way but do not offer direct element access.

In conclusion, while performance is a crucial factor, choosing between `.at()` and bracket notation should also consider readability, maintainability, and environment requirements.

Related benchmarks:

.at vs bracket notation (version: 0)

.at vs bracket notation

Comparing performance of: .at vs bracket

Created: one year ago by: Guest

Jump to the latest result

.at

bracket

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):