Benchmark: array destructuring vs direct access 2

Script Preparation code:


const names = ["first", "middle", "last", "suffix"]

Tests:

names[0]
const firstName = ["first", "middle", "last", "suffix"][0];
array filter
const [firstName] = ["first", "middle", "last", "suffix"];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
names[0]
array filter

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/136.0.0.0 Safari/537.36

Browser/OS: Chrome 136 on Mac OS X 10.15.7

View result in a separate tab

names[0]

154.1M/s

array filter

153.7M/s

View exact numbers

Test name	Executions per second
✓ names[0]	154,102,064 Ops/sec
array filter	153,675,200 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and explain what's being tested.

**Benchmark Definition**

The benchmark is comparing two approaches to accessing an array element: direct access using bracket notation (`names[0]`) versus array destructuring with square brackets (`const [firstName] = [\"first\", \"middle\", \"last\", \"suffix\"];`).

**Options Compared**

There are two options being compared:

1. **Direct Access**: Using the `[]` syntax to access an element in an array, as shown in the first test case: `const firstName = [\"first\", \"middle\", \"last\", \"suffix\"][0];`.
2. **Array Destructuring**: Using destructuring assignment with square brackets, as shown in the second test case: `const [firstName] = [\"first\", \"middle\", \"last\", \"suffix\"];`.

**Pros and Cons of Each Approach**

* **Direct Access**
	+ Pros:
		- Simple and straightforward.
		- No need to create a new variable or array.
	+ Cons:
		- May require more memory allocation, depending on the size of the array.
		- Can be slower due to the need to calculate the index (in this case, `[0]`).
* **Array Destructuring**
	+ Pros:
		- More concise and readable.
		- No need to create a new variable or array.
		- Can improve code readability by avoiding the `[]` syntax.
	+ Cons:
		- May be slower due to the overhead of creating a temporary array.
		- Requires support for destructuring assignment in JavaScript (introduced in ECMAScript 2015).

**Library and Purpose**

In this benchmark, there is no specific library being tested. However, it's worth noting that the `[]` syntax used for direct access is a built-in feature of JavaScript arrays.

**Special JS Feature or Syntax**

The test case uses array destructuring with square brackets (`const [firstName] = ...;`). This is a relatively recent feature introduced in ECMAScript 2015 (also known as ES6). It's a concise way to extract multiple values from an array into separate variables. The `[]` syntax creates a new array from the original array, which can be slower than direct access.

**Other Considerations**

* **Cache Locality**: When accessing elements in an array, the JavaScript engine may use cache locality to improve performance. In this case, direct access may benefit from cache locality since it only accesses a single element.
* **Memory Allocation**: The test cases allocate memory for the original array and the temporary variables (e.g., `firstName`). This can affect performance, especially if the array is large.

**Alternatives**

Other approaches to accessing array elements include:

1. Using the `slice()` method or `array.prototype.slice.call()` to extract a subset of array elements.
2. Creating a new array with `Array.from()` and then extracting the desired element(s) using indexing.
3. Using a custom loop or recursion to iterate through the array.

However, these approaches are not directly comparable to direct access or array destructuring in terms of performance.

array destructuring vs direct access 2 (version: 0) Benchmark.js

Comparing performance of: `names[0] vs array filter`

Created: 6 years ago by: Guest

Go to the latest result

names[0]

array filter

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

array destructuring vs direct access 2 (version: 0) Benchmark.js

Comparing performance of: names[0] vs array filter

Created: 6 years ago by: Guest

Go to the latest result

names[0]

array filter

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `names[0] vs array filter`