Benchmark: slice VS splice VS shift: removing an elmeent from the middle

Script Preparation code:

var list = [];
var index = 50000
for (var i = 0; i < 1000 * 1000; i++) {
  list.push(i);
}

Tests:

slice
const firstArr = list.slice(0, index); const secondArr = list.slice(index + 1); list = [...firstArr , ...secondArr]
splice
list.splice(index, 1);

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:

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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 explain what's being tested, compared, and its pros and cons.

**What's being tested:**

The benchmark compares the performance of two methods to remove an element from the middle of a large list:

1. `slice()`: Creates a shallow copy of the original array using the `slice()` method.
2. `splice()`: Modifies the original array in place by removing the specified number of elements.

**Options compared:**

The benchmark only compares these two methods, but there are other approaches to remove an element from an array, such as:

* Using `filter()` with a callback function: `list.filter((element) => element !== index)`
* Using `map()` and then concatenating the results: `list.slice(0, index).concat(list.slice(index + 1))`
* Using a custom implementation using indexing and slicing: `var temp = list[index]; list.splice(index, 1); return [...list, temp]`

These alternatives are not tested in this benchmark.

**Pros and cons of each approach:**

1. **slice()**: Creates a shallow copy of the original array.
	* Pros: Immutable, efficient, easy to read.
	* Cons: Creates an additional object reference, can be slower than in-place modifications.
2. **splice()**: Modifies the original array in place.
	* Pros: Efficient, modifies the original data structure.
	* Cons: Mutates the original array, may not be suitable for all use cases.

**Library usage:**

The benchmark uses the `slice()` method from the built-in JavaScript Array prototype, which is a part of the ECMAScript standard and does not require any external libraries or dependencies.

**Special JS feature/syntax:**

There are no special JavaScript features or syntaxes used in this benchmark. The code is written in plain JavaScript and only uses standard library functions.

**Other considerations:**

* The benchmark creates a large list (100,000 elements) to simulate real-world scenarios where data structures need to be modified frequently.
* The `index` variable is set to 50,000, which means that the element being removed is not at the beginning or end of the list. This simulates a scenario where elements are inserted in between existing elements.

**Alternatives:**

If you want to explore other approaches to remove an element from an array, here are some alternatives:

Keep in mind that these alternatives may have different performance characteristics and use cases compared to the `slice()` and `splice()` methods.

Related benchmarks:

slice VS splice VS shift: removing an elmeent from the middle (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: Registered User

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):