Benchmark: Array Splice vs Concat

Tests:

Array.prototype.concat
const length = 100000; const a1 = new Array(length).fill(1) const a2 = new Array(length).fill(2) const a3 = a1.concat(a2)
Array.prototype.splice
const length = 100000; const a1 = new Array(length).fill(1) const a2 = new Array(length).fill(2) const a4 = new Array(length * 2) a4.splice(0, a1.length, ...a1) a4.splice(a1.length, a2.length, ...a2)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.prototype.concat
Array.prototype.splice

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark definition and test cases to understand what is being tested.

**Benchmark Definition:**

The benchmark is designed to compare two approaches for manipulating arrays in JavaScript:

1. `Array.prototype.concat()`: This method creates a new array by concatenating two or more arrays together. It returns a new array object with the elements of all the arrays.
2. `Array.prototype.splice()`: This method modifies the existing array by removing or replacing elements and returns an array containing the removed elements.

**Options Compared:**

The benchmark compares the performance of these two approaches:

* `concat()` vs. `splice()`
* Creating a new array (`concat()`) vs. modifying the existing array (`splice()`)

**Pros and Cons:**

1. **`concat()`**: Pros:
	* Creates a new array, which can be more efficient than modifying an existing array.
	* Returns a new array object with the elements of all arrays.
Cons:
	* Creates a new array object, which requires additional memory allocation.
2. **`splice()`**: Pros:
	* Modifies the existing array in place, reducing memory allocation.
	* Can be faster for large arrays since it doesn't create a new array object.
Cons:
	* Changes the original array, which can be unexpected behavior for some users.
	* Returns an array containing the removed elements.

**Library and Special Features:**

There are no libraries mentioned in the benchmark definition. However, JavaScript has some special features that may affect the performance of these tests:

1. **`let` and `const` declarations**: The benchmark uses `const` declarations for variable assignments, which can lead to more efficient memory management.
2. **Array initializers**: The use of array initializers (`new Array(length).fill(1)` or `a4.splice(0, a1.length, ...a1)`) may also impact performance.

**Other Alternatives:**

For manipulating arrays in JavaScript, other approaches exist:

1. **`push()` and `unshift()`**: These methods add elements to the end or beginning of an array, respectively.
2. **`forEach()` and `map()`**: These methods iterate over arrays without modifying them.
3. **`slice()`**: This method creates a shallow copy of an array.

However, these alternatives may not be as efficient as `concat()` for certain use cases, such as concatenating large arrays or inserting elements at specific positions.

Overall, the benchmark provides valuable insights into the performance differences between `concat()` and `splice()` in JavaScript.

Related benchmarks:

Array Splice vs Concat (version: 0)

Comparing performance of: Array.prototype.concat vs Array.prototype.splice

Created: 3 years ago by: Guest

Jump to the latest result

Array.prototype.concat

Array.prototype.splice

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):