Benchmark: Spred vs Slice - MeasureThat.net

Tests:

Spread
const array = [...Array(1000).keys()]; const result = [...array];
Slice
const array = [...Array(1000).keys()]; const result = array.slice();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread
Slice

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36

Browser/OS: Chrome 112 on Linux

View result in a separate tab

Test name	Executions per second
Spread	25753.8 Ops/sec
Slice	26031.3 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and its test cases.

**What is being tested?**

The test case compares two ways of creating a copy of an array in JavaScript: using the spread operator (`...`) and the `slice()` method.

**Options compared:**

1. **Spread Operator (```...)**: This operator creates a new array by spreading the elements of an existing array or iterable.
2. **Slice Method (`array.slice()`)**: The `slice()` method returns a shallow copy of a portion of an array, starting from the index you specify.

**Pros and Cons:**

1. **Spread Operator (```...)**:
	* Pros: concise, easy to read, and flexible (can be used with arrays, objects, sets, etc.).
	* Cons: may incur a higher overhead due to its syntactic sugar, which can lead to slightly slower performance.
2. **Slice Method (`array.slice()`)**:
	* Pros: well-established, widely supported, and often considered the "traditional" way of creating an array copy.
	* Cons: less concise than the spread operator, and its syntax may be less readable for some developers.

**Other Considerations:**

Both approaches have their advantages and disadvantages. The choice between them ultimately depends on personal preference, code readability, and performance considerations.

If you need to create a deep copy of an array (i.e., recursively copying nested arrays or objects), the spread operator might not be suitable due to its shallow copying nature.

**Library Usage:**

None of the provided test cases uses any external libraries. The only library-like functionality is the `Array` object itself, which provides various methods for manipulating and accessing array elements.

**Special JS Feature/Syntax:**

There are no special JavaScript features or syntax used in these test cases. The focus is on comparing two fundamental ways of creating an array copy.

**Benchmark Result Analysis:**

The provided benchmark result shows that the `slice()` method outperforms the spread operator in this specific scenario, with Chrome 112 executing the `slice()` method approximately 78 executions per second faster than the spread operator. However, it's essential to note that this result may vary depending on the specific JavaScript engine, browser version, and platform used.

**Alternatives:**

Other alternatives for creating array copies include:

1. **Array.prototype.map()**: While not a traditional way of creating an array copy, `map()` can be used with an identity function (e.g., `(x) => x`) to create a shallow copy of an array.
2. **For...of loop**: A manual loop using a `for...of` loop and the `push()` method or the spread operator (`...`) to create an array copy.

Keep in mind that these alternatives might have different performance characteristics, readability, and maintainability trade-offs compared to the slice() method or spread operator.

Related benchmarks:

Spred vs Slice (version: 0)

Comparing performance of: Spread vs Slice

Created: 3 years ago by: Guest

Jump to the latest result

Spread

Slice

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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