Benchmark: Spread Operator VS Array.prototype.slice() VS Array.prototype.map()

Script Preparation code:

var randomNumbers = [];
for (let i = 0; i < 2000; i++) {
    randomNumbers.push(Math.random());
}

Tests:

Spread Operator
const spreadOperator = [...randomNumbers];
Array.prototype.slice()
const slice = randomNumbers.slice();
Array.prototype.map()
const map = randomNumbers.map(num=>num);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread Operator
Array.prototype.slice()
Array.prototype.map()

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Windows

View result in a separate tab

Test name	Executions per second
Spread Operator	1680759.9 Ops/sec
Array.prototype.slice()	1725002.2 Ops/sec
Array.prototype.map()	295365.9 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 benchmark preparation code to understand what is being tested.

**Benchmark Definition**

The `Spread Operator VS Array.prototype.slice() VS Array.prototype.map()` benchmark tests three different approaches to create a shallow copy of an array:

1. **Spread Operator**: The spread operator (`...`) creates a new array by copying elements from the original array.
2. **Array.prototype.slice()**: The `slice()` method returns a shallow copy of a portion of an array, starting from the beginning and ending at the specified index.
3. **Array.prototype.map()**: The `map()` method applies a provided function to each element in the array and returns a new array with the results.

**Pros and Cons**

* **Spread Operator**: Pros:
	+ Concise and readable syntax
	+ Fast performance (since it's a native operator)
Cons:
	+ Can be slower for very large arrays due to JavaScript's garbage collection overhead
* **Array.prototype.slice()**: Pros:
	+ Efficient and optimized for large datasets
Cons:
	+ Less readable syntax than the spread operator or `map()`
	+ May have performance issues if not implemented correctly (e.g., using `slice()` with a negative index)
* **Array.prototype.map()**: Pros:
	+ More expressive syntax than `slice()`, making it easier to understand and maintain
Cons:
	+ Can be slower for very large arrays due to the overhead of applying the provided function to each element

**Library Usage**

None of the test cases use any external libraries, so there are no additional dependencies to consider.

**Special JS Features or Syntax**

* **Spread Operator**: Introduced in ECMAScript 2018 (ES2018), the spread operator is a new syntax for creating arrays from iterables. It's supported by most modern browsers and JavaScript engines.
* **Array.prototype.slice()**: A standard method of the Array prototype, which has been available since ECMAScript 5 (ES5).
* **Array.prototype.map()**: Also a standard method of the Array prototype, introduced in ECMAScript 5 (ES5).

**Other Alternatives**

For creating shallow copies of arrays, other approaches include:

* Using `Array.from()` with an iterable argument
* Using `Object.assign()` with an array as the first argument
* Using `Lodash` or other utility libraries that provide a `cloneDeep()` function for deep copying arrays

Keep in mind that the choice of approach often depends on specific use cases, performance requirements, and personal coding style.

**Benchmark Considerations**

When interpreting the benchmark results:

* Look at the raw execution count per second (e.g., 1725002.25) to understand which method performs best for a given number of executions.
* Compare the results across different browsers or devices to see if there are any platform-specific differences in performance.
* Check if the benchmark is running on a stable, repeatable environment to ensure accurate results.

These considerations help you make informed decisions about choosing the right approach for your specific use cases.

Related benchmarks:

Spread Operator VS Array.prototype.slice() VS Array.prototype.map() (version: 0)

Spread Operator VS Array.prototype.slice() VS Array.prototype.map()

Comparing performance of: Spread Operator vs Array.prototype.slice() vs Array.prototype.map()

Created: 2 years ago by: Registered User

Jump to the latest result

Spread Operator

Array.prototype.slice()

Array.prototype.map()

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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