Benchmark: javascript spread

Script Preparation code:

data = [...Array(1000).keys()]

Tests:

spread
data.reduce((acc, item) => { return [...acc, item]; }, [])
push
data.reduce((acc, item) => { acc.push(item); return acc; }, [])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread
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 explanation of the provided benchmark.

**What is being tested?**

The benchmark measures the performance difference between two approaches to achieve the same result:

1. Using `Array.prototype.push()` method to add elements to an array.
2. Using spread operator (`...`) to create a new array by copying existing elements.

The test cases are based on the JavaScript Array prototype, which is implemented in C++ and compiled into machine code for execution.

**Options compared**

There are two options being compared:

1. **`push()` method**: This is a built-in method of the Array prototype that adds an element to the end of an array.
2. **Spread operator (`...`)**: This is a new operator introduced in ECMAScript 2015 (ES6) that allows creating a new array by copying existing elements.

**Pros and Cons**

* **`push()` method**:
	+ Pros: Simple, widely supported, and well-understood by developers.
	+ Cons: It creates a new copy of the entire array on each push operation, which can be inefficient for large arrays.
* **Spread operator (`...`)**:
	+ Pros: More efficient than `push()`, as it only copies the necessary elements. This makes it suitable for large arrays.
	+ Cons: Less widely supported and understood by developers.

**Library**

There is no explicit library mentioned in the benchmark, but both approaches rely on the JavaScript Array prototype implementation. The spread operator was introduced in ECMAScript 2015 (ES6), so older browsers may not support it.

**Special JS feature or syntax**

The spread operator (`...`) is a new syntax introduced in ES6. It's a shorthand for creating a new array by copying existing elements: `const arr = [...existingArr];`. This syntax was added to improve code readability and performance.

**Other alternatives**

There are other ways to achieve the same result, such as using `Array.prototype.concat()` or looping through the original array:

```javascript
// Using Array.prototype.concat()
arr.push(...existingArr);

// Loops
for (const item of existingArr) {
  arr.push(item);
}
```

However, these alternatives are less efficient and more verbose than using the spread operator.

**Benchmark preparation code**

The provided script prepares an array `data` with 1000 elements by generating keys from 0 to 999. This array is used as input for both test cases.

In summary, the benchmark measures the performance difference between two approaches to add elements to an array: using the `push()` method and the spread operator (`...`). The spread operator offers better performance but requires a modern browser that supports it.

Related benchmarks:

javascript spread (version: 0)

Comparing performance of: spread vs push

Created: 2 years ago by: Guest

Jump to the latest result

spread

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):