Benchmark: slice VS splice VS shift: who is the fastest to pass all array

Script Preparation code:

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

Tests:

slice
list.push('slice'); while (list.length) { let list2 = list.slice(1, 50); list.splice(0, 50); }
splice
list.push('splice'); while (list.length) { let list2 = list.splice(0, 50); }

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 break down the provided benchmark and its components.

**Benchmark Definition**

The benchmark is defined by two benchmark definitions in JSON format, which represent individual test cases. The first one is for testing the performance of `slice()` and `shift()`, while the second one tests the performance of just `slice()`. Both test cases use a 100k-element array as input.

Here's what's being tested:

* In both benchmark definitions, an empty array `list` is initialized using `var list = []`.
* A large array (1000 elements) is populated with numbers from 0 to 9999 using `for` loop.
* The test case uses a while loop that continues until the `list.length` is greater than 0. In each iteration, a new variable `list2` is created by slicing the first 50 elements of the original array using `list.slice(1, 50)`.
* In one of the benchmark definitions (`splice`), after creating `list2`, the first 50 elements are removed from the original array using `list.splice(0, 50)`.
* The second benchmark definition only uses `slice()` without modifying the original array.

**Options Compared**

Two options are being compared:

1. **Using `splice()`**: This approach modifies the original array by removing the first 50 elements.
	* Pros:
		+ Only one operation is performed on the original array (removing).
		+ Can be more efficient if the array needs to be modified later.
	* Cons:
		+ Modifies the original array, which can lead to unexpected side effects.
		+ May require additional cleanup code if not used carefully.
2. **Using `slice()`**: This approach creates a new array by slicing the original array and returns it without modifying it.
	* Pros:
		+ Does not modify the original array, preserving its integrity.
		+ Can be more predictable and easier to reason about.
	* Cons:
		+ Creates a new array object, which can lead to increased memory usage.

**Library**

There is no specific library being used in these benchmark definitions. However, it's worth noting that `slice()` and `splice()` are built-in JavaScript methods that don't require any external libraries.

**Special JS Features or Syntax**

The benchmark uses modern JavaScript features such as:

* **Template literals**: Used for creating the initial array using `for` loop (`var list = [];\r\nfor (var i = 0; i < 1000 * 1000; i++) {\r\n  list.push(i);\r\n}`).
* **Arrow functions**: Not explicitly used, but implicit arrow function is created when defining the while loop.

**Other Alternatives**

If you wanted to test these same benchmark definitions using alternative approaches, you could consider:

1. Using `concat()` instead of `slice()`: Create a new array by concatenating arrays.
2. Using an array comprehension or map function: Create a new array by mapping over the original array.
3. Using `filter()` and `map()` to create a new array: Filter out elements that don't meet a certain condition and then map each element to a new value.

However, since these alternatives would require significant changes to the benchmark definition and might not accurately represent the performance characteristics of the original code, it's recommended to stick with the original implementation.

Related benchmarks:

slice VS splice VS shift: who is the fastest to pass all array (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: 4 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):