Benchmark: slice VS splice VS shift: who is the fastest to keep constant size after adding multiple

Script Preparation code:

var list = [];
for (var i = 0; i < 1000000; i++) {
  list.push(i);
}

Tests:

slice
for (var i = 0; i < 100; i++) { list.push(i); } list = list.slice(100);
splice
for (var i = 0; i < 100; i++) { list.push(i); } list.splice(0, 100);
shift
for (var i = 0; i < 100; i++) { list.push(i); } for (var i = 0; i < 100; i++) { list.shift(); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
splice
shift

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 its options.

**Benchmark Overview**

The benchmark measures which method is fastest to keep the size of a list constant after adding multiple elements: using `splice`, `shift`, or `slice`. The test case uses an array of 100,000 elements, and each operation is performed on this list 7.5 times faster than the other methods.

**Options Compared**

The benchmark compares three options:

1. **Slice**: Using the `slice()` method to create a copy of the original list.
2. **Splice**: Using the `splice()` method to remove elements from the beginning of the list, effectively keeping its size constant.
3. **Shift**: Using the `shift()` method to remove the first element from the end of the list, also keeping its size constant.

**Pros and Cons of Each Approach**

1. **Slice**:
	* Pros: Creates a new copy of the original list, which can be beneficial for preserving the original data.
	* Cons: Can be slower than `splice` or `shift`, as it creates a new object with the same elements.
2. **Splice**:
	* Pros: Fast and efficient, as it only modifies the existing array object.
	* Cons: Mutates the original list, which can have unintended consequences if the list is used elsewhere in the code.
3. **Shift**:
	* Pros: Also fast and efficient like `splice`, but with less overhead due to not removing elements from the beginning of the array.
	* Cons: May be slower than `splice` for large arrays due to the extra iteration required.

**Library Used**

None is explicitly mentioned in the benchmark definition or individual test cases. However, it's likely that these benchmarks are testing the built-in JavaScript methods and should work on any modern browser or JavaScript engine without external libraries.

**Special JS Features or Syntax**

The only special feature used here is a non-standard way of using `splice()` with an index of 0 and an amount of 100. While this syntax might be useful in certain scenarios, it's not commonly seen in everyday coding practices.

**Other Alternatives**

If you wanted to modify the list while keeping its size constant but without using these three methods, you could consider using other approaches such as:

* Using `map()` or `filter()` with a callback function that removes elements from the beginning of the array.
* Creating a new array and pushing/populating it with data.
* Using a library like Lodash's `tail()` or `takeRight()` functions.

Keep in mind that these alternatives might have different performance characteristics, depending on the specific use case.

Related benchmarks:

slice VS splice VS shift: who is the fastest to keep constant size after adding multiple (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 vs shift

Created: 4 years ago by: Guest

Jump to the latest result

slice

splice

shift

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):