Benchmark: slice VS splice many items

Script Preparation code:

var list = [];
for (var i = 0; i < 1000 * 1000; i++) {
  list.push(i);
}

Tests:

slice
list.push('slice'); list = list.slice(1000);
splice
list.push('splice'); list.splice(0, 1000);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
splice

Fastest: N/A

Slowest: N/A

Latest run results:

No previous 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 world of JavaScript microbenchmarks on MeasureThat.net.

**What is being tested?**

The provided benchmark measures the performance difference between two approaches: using `Array.prototype.slice()` and `Array.prototype.splice()` to manipulate an array with a large number of elements (100,000).

**Options compared**

There are two options being compared:

1. **`slice()`**: This method creates a shallow copy of a portion of an array, leaving the original array unchanged.
2. **`splice()`**: This method removes or replaces elements in an array and returns the number of elements removed.

**Pros and Cons:**

* `slice()`: 
	+ Pros:
		- Creates a new array, leaving the original array intact.
		- Can be faster for large arrays because it doesn't modify the original array.
	+ Cons:
		- Requires creating a new array, which can consume more memory.
		- May not be suitable for situations where modifying the original array is necessary.
* `splice()`: 
	+ Pros:
		- Modifies the original array, reducing memory allocation and deallocation overhead.
		- Can be faster because it modifies the existing array without creating a new one.
	+ Cons:
		- Modifies the original array, potentially affecting other parts of the code that rely on its state.
		- May be slower for very large arrays due to the overhead of modifying the array.

**Library and purpose**

There is no library mentioned in the benchmark definition or test cases. The tests only involve standard JavaScript syntax and built-in methods.

**Special JS feature or syntax**

None are explicitly mentioned, but some JavaScript versions have introduced features like `const` and `let` that can affect how arrays are manipulated.

**Other alternatives**

For manipulating arrays, other approaches include:

1. **`Array.prototype.map()`**: Creates a new array with the results of applying a provided function to each element in the original array.
2. **`Array.prototype.reduce()`**: Applies a reduction function to all elements in an array, reducing it to a single output value.

While these methods can be useful for specific use cases, they might not be as suitable for this particular benchmark due to the large size of the array and the need to manipulate individual elements.

**Benchmark preparation code**

The script preparation code creates an empty array `list` and populates it with 1 million elements using a `for` loop. This ensures that the test case is run on a large enough dataset to measure any performance differences between the two approaches.

**Individual test cases**

Each test case consists of a single benchmark definition, which includes:

1. A JavaScript statement that executes either `list.push('slice')` or `list.push('splice')`.
2. The resulting assignment of the result back to the `list` variable.

These statements are then executed multiple times to gather execution statistics for each approach.

Related benchmarks:

slice VS splice many items (version: 0)

100k list splice and shift win, they mutate list slice loose, it creates a copy of list 7.5x slower

Comparing performance of: slice vs splice

Created: 3 years ago by: Guest

Jump to the latest result

slice

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):