Benchmark: spread vs slice 1000 array entries

Tests:

spread
const arrayOfThings = [...Array(1000)].map(() => { const randomStr = "abcdefghijklmnopqrstuvwxyz".split('').sort(() => .5-Math.random()).join(''); return randomStr.slice(0, Math.random()*26 + 2) }) const sortedArray = [...arrayOfThings].sort() console.log(sortedArray)
slice
const arrayOfThings = [...Array(1000)].map(() => { const randomStr = "abcdefghijklmnopqrstuvwxyz".split('').sort(() => .5-Math.random()).join(''); return randomStr.slice(0, Math.random()*26 + 2) }) const sortedArray = arrayOfThings.slice().sort() console.log(sortedArray)

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:

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

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

**Benchmark Definition**
The benchmark is defined in JSON format, which provides basic information about the benchmark, such as its name, description, script preparation code, and HTML preparation code (which are empty in this case).

**Test Cases**
There are two test cases:

1. **"spread"`: This test case uses the spread operator (`[...Array(1000)]`) to create an array with 1000 elements. Each element is a function that generates a random string, sorts it using `Math.random()` as the sorting function, and then returns a slice of the first 26 characters plus a random offset between 2 and 26 (inclusive). The test case then sorts this array using the spread operator again and logs the result to the console.
2. **"slice"`: This test case is similar to the "spread" test case, but instead of using the spread operator, it uses the `Array.prototype.slice()` method to create a copy of the original array before sorting it.

**Options Compared**
The two test cases compare the performance of using the spread operator versus the `Array.prototype.slice()` method when creating an array and then sorting it.

**Pros and Cons**

* **Spread Operator ( "[...Array(1000)]" )**:
	+ Pros: Creates a new array with the desired number of elements, can be used to create arrays with dynamic lengths.
	+ Cons: Can be slower than `Array.prototype.slice()` for large arrays due to the overhead of creating a new array and copying the data.
* **`Array.prototype.slice()` Method**:
	+ Pros: Faster than the spread operator for large arrays, creates a shallow copy of the original array (which can be beneficial for mutable data).
	+ Cons: Can lead to slower performance if used on very large arrays or when sorting is not necessary.

In general, using the spread operator can provide more flexibility and conciseness in code, but may come at a cost in terms of performance. The `Array.prototype.slice()` method, on the other hand, provides better performance for creating new arrays with specific lengths, especially when sorting is not necessary.

**Library Used**
There are no external libraries used in these test cases.

**Special JS Feature or Syntax**
The use of `Math.random()` as the sorting function in both test cases introduces a random element to the benchmark. While this makes it more representative of real-world scenarios where sorting might be done with random input, it also means that the results may vary between runs due to the randomization.

**Other Considerations**

* The size of the array (1000 elements) is relatively small, so the performance differences between the spread operator and `Array.prototype.slice()` method may not be as pronounced.
* Both test cases use a simple sorting algorithm (built-in sort), which might not be representative of more complex scenarios where other algorithms or libraries are used.

**Alternatives**

Other alternatives to testing array creation and sorting in JavaScript include:

* Using `new Array(1000)` instead of the spread operator for an exact same length.
* Comparing performance with different sorting algorithms, such as quicksort or mergesort.
* Using a larger array size (e.g., 10,000 elements) to see if the performance differences between the two approaches become more pronounced.
* Testing the performance of other methods for creating arrays, such as `Array.from()` or `concat()`.

Related benchmarks:

spread vs slice 1000 array entries (version: 0)

Comparing performance of: spread vs slice

Created: 4 years ago by: Guest

Jump to the latest result

spread

slice

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):