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

Test name	Executions per second
names[0]	154102064.0 Ops/sec
array filter	153675200.0 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.

Related benchmarks:

array destructuring vs direct access 2 (version: 0)

Comparing performance of: names[0] vs array filter

Created: 6 years ago by: Guest

Jump 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):