Benchmark: Array Copy: Spread operator VS For loop

Tests:

Spread
const original = [1,2,3,4,5,6,7,8,9,10] const result = [...original];
For loop
const original = [1,2,3,4,5,6,7,8,9,10] const result = [] for (let i in original) { result[i] = original[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread
For loop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36

Browser/OS: Chrome 138 on Windows

View result in a separate tab

Test name	Executions per second
Spread	77137280.0 Ops/sec
For loop	2776012.5 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 JSON and explain what is tested in the benchmark, along with the options being compared, pros and cons of each approach, and other considerations.

**Benchmark Definition**
The benchmark definition represents a simple JavaScript microbenchmark that tests two approaches for copying an array: using the spread operator (`...`) versus a traditional `for` loop.

**Options Being Compared**

1. **Spread Operator (ES6+ syntax)**:
	* Method: `const result = [...original];`
	* Purpose: Create a new array by spreading the elements of the original array.
	* Pros:
		+ Concise and readable syntax.
		+ Efficient, as it creates a new array without modifying the original one.
	* Cons:
		+ May have performance overhead due to the additional operation (spreading).
2. **Traditional `for` loop**:
	* Method: `const result = []; for (let i in original) { result[i] = original[i]; }`
	* Purpose: Use a traditional `for` loop to iterate over the elements of the original array and populate the new array.
	* Pros:
		+ May be optimized by the JavaScript engine, as it's a more familiar pattern.
	* Cons:
		+ Less concise and less readable syntax compared to the spread operator.
		+ May modify the original array (although this can be mitigated with slicing or concatenation).

**Library Usage**
None of the test cases use any external libraries.

**Special JS Features/Syntax**
There are no special JavaScript features or syntax used in these benchmark definitions. They only rely on standard ECMAScript 6+ features and the `for` loop.

**Other Considerations**

* The benchmark assumes that the original array is large enough to warrant noticeable performance differences between the two approaches.
* It's worth noting that modern JavaScript engines are optimized for the spread operator, making it generally faster than traditional `for` loops for small arrays. However, for very large arrays, a traditional loop might still be more efficient due to the overhead of spreading.

**Alternative Approaches**

Some alternative approaches could be:

1. **Using `Array.prototype.slice()` or `Array.prototype.concat()`:**
	* These methods can create new arrays without modifying the original one.
2. **Using `JSON.parse(JSON.stringify(original))` ( deprecated ):**
	* This method has performance issues and is generally discouraged for its side effects on object prototypes.
3. **Using a library like Lodash's `cloneDeep()` or `_.times()`:**
	* These libraries provide optimized cloning functions that might outperform the spread operator or traditional loops, depending on the specific use case.

The benchmark results are likely comparing the performance of these different approaches in a controlled environment, allowing users to compare and contrast their performance on their own systems.

Related benchmarks:

Array Copy: Spread operator VS For loop (version: 0)

Comparing performance of: Spread vs For loop

Created: one year ago by: Guest

Jump to the latest result

Spread

For loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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