Benchmark: spread operator (...) vs iterating to copy array

Script Preparation code:

var obj = {
	prop: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]
};

Tests:

spread
var newObj = { prop: [] }; newObj.prop = [...obj.prop];
iterative
var newObj = { prop: [] }; let orig = obj.prop; for (let i = 0; i < orig.length; i++) { newObj.prop[i] = orig[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread
iterative

Fastest: N/A

Slowest: N/A

Latest run results:

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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 and explain what is being tested.

**Benchmark Overview**

The benchmark compares two approaches to create a copy of an array: using the spread operator (`...`) and iterating manually by assigning each element to a new array.

**Options Being Compared**

1. **Spread Operator (`...`)**: This method creates a new array by spreading the elements of the original array into a new array. For example, `var newObj = {...obj.prop};`.
2. **Iterative Copy**: This method manually iterates over each element of the original array and assigns it to a new array. For example, `var newObj = { prop: [] }; let orig = obj.prop; for (let i = 0; i < orig.length; i++) { newObj.prop[i] = orig[i]; }`.

**Pros and Cons**

* **Spread Operator (`...`)**:
	+ Pros:
		- Concise and expressive syntax.
		- Fast execution, as it uses a built-in operator.
		- Less prone to errors due to its simplicity.
	+ Cons:
		- May not be supported in older browsers or environments that don't support modern JavaScript features.
* **Iterative Copy**:
	+ Pros:
		- Widely supported across different browsers and environments, as it's a basic programming concept.
		- Can be useful when working with legacy code or ensuring compatibility.
	+ Cons:
		- More verbose syntax can lead to errors if not implemented carefully.
		- Slower execution compared to the spread operator.

**Library/Dependency Used**

None of the provided benchmark test cases rely on external libraries. However, it's worth noting that both approaches are native JavaScript features and don't require any external dependencies.

**Special JS Feature or Syntax**

There is no special JavaScript feature or syntax being tested in this benchmark. Both approaches use standard JavaScript syntax and don't rely on any proprietary or experimental features.

**Other Alternatives**

If you wanted to create a copy of an array, there are other alternatives available:

1. **`Array.prototype.slice()`**: This method creates a shallow copy of the original array by slicing it into a new array.
2. **`Array.prototype.concat()`**: This method creates a new array that is a concatenation of the original array and another array (or multiple arrays).
3. **`Array.prototype.map()`**: While not directly used for creating an array copy, `map()` can be used in combination with other methods to create a new array.

Keep in mind that these alternatives might have slightly different performance characteristics or behavioral differences compared to the spread operator or iterative copy approaches.

I hope this explanation helps software engineers understand what's being tested in this benchmark and how to approach similar comparisons in their own JavaScript projects!

Related benchmarks:

spread operator (...) vs iterating to copy array (version: 0)

Comparing performance of: spread vs iterative

Created: 3 years ago by: Guest

Jump to the latest result

spread

iterative

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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