Benchmark: spread vs forEach push

Script Preparation code:

var arr = Array.from(Array(1000).keys())

Tests:

spread
var brr = [...arr] var crr = arr.slice().reverse()
forEach push
var drr = [] var err = [] arr.forEach(item => { drr.push(item) err.unshift(item) })

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread
forEach push

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 dive into the Benchmark Definition and test cases.

**Benchmark Definition**

The benchmark is testing the performance of two approaches to create a reversed copy of an array:

1. **Spread Operator (`...`)**: This approach uses the spread operator to create a new array by spreading the original array.
2. **`forEach()` and `push()`**: This approach uses the `forEach()` method to iterate over the original array and push each element into a new array using the `push()` method.

**Options Compared**

The benchmark is comparing two options:

* `var brr = [...arr]`: Creates a new array by spreading the original array.
* `var crr = arr.slice().reverse()`: Creates a new reversed copy of the original array using the `slice()` method and reversing it using the `reverse()` method.

**Pros and Cons**

1. **Spread Operator (`...`)**:
	* Pros: concise, efficient, and readable.
	* Cons: may not be supported in older browsers or versions of JavaScript.
2. **`forEach()` and `push()`**:
	* Pros: widely supported, can handle large arrays, and allows for custom logic.
	* Cons: may be slower than the spread operator due to the iteration and push operations.

**Library and Special JS Feature**

In this benchmark, there is no explicit library mentioned. However, it's worth noting that some browsers or environments might have built-in optimizations or polyfills for certain JavaScript features.

**Other Considerations**

* The benchmark uses a fixed array size of 1000 elements to create the original array.
* The `forEach()` method is used with an arrow function (`item => { ... }`) to simplify the code and improve readability.
* The `push()` method is used in combination with the `unshift()` method (not explicitly mentioned, but inferred) to build the reversed copy of the array.

**Alternatives**

Some alternative approaches to create a reversed copy of an array could include:

* Using `Array.prototype.reverse()`: This method reverses the original array in-place and returns the modified array.
* Using `Array.prototype.map()` and `Array.prototype.concat()`: This approach creates a new array by mapping each element of the original array to a new value and then concatenating the results.

However, these approaches might not be as concise or efficient as the spread operator or the `forEach()` and `push()` combination used in this benchmark.

Related benchmarks:

spread vs forEach push (version: 0)

Comparing performance of: spread vs forEach push

Created: 2 years ago by: Registered User

Jump to the latest result

spread

forEach push

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):