Benchmark: slice VS splice VS shift: who is the fastest to keep constant size v2

Script Preparation code:

var list = [];
for (var i = 0; i < 100; i++) {
  list.push(i);
}

Tests:

slice
list.push(30000); list = list.slice(1);
splice
list.push(30000); list.splice(0, 1);
shift
list.push(30000); 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):

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Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Overview**

The benchmark measures the performance of three ways to remove elements from an array while keeping its size constant: `splice`, `shift`, and `slice`. The test creates a long list of numbers, pushes 30,000 onto it, and then removes the first element using each method.

**Library Used**

In this benchmark, no specific library is used. However, JavaScript arrays are built-in objects that provide these methods for modifying their contents without changing the array's size.

**Options Compared**

The options compared in this benchmark are:

1. `splice`: Removes elements from an array by specifying the start and end indices.
2. `shift`: Removes the first element from an array and returns it.
3. `slice`: Creates a shallow copy of a subset of an array, excluding the slice's end index.

**Pros and Cons**

Here are some pros and cons of each approach:

*   **splice**: 
    *   Pros: flexible, allows for removing multiple elements at once.
    *   Cons: can be slower than `shift` or `slice` when removing a single element, as it involves re-indexing the array's contents.
*   **shift**:
    *   Pros: fastest method among the three, returns removed element.
    *   Cons: only removes the first element from the array; if you need to remove multiple elements, `splice` is more suitable.
*   **slice**:
    *   Pros: creates a new array object, doesn't modify the original array.
    *   Cons: can be slower than `shift`, as it involves creating a new array with the specified subset.

**Special JavaScript Feature or Syntax**

The benchmark uses the `push` method to append elements to an array. The `push` method is a special method in JavaScript arrays that appends one or more elements to the end of the array and returns the new length of the array.

**Other Considerations**

When dealing with large arrays, it's essential to consider the following:

*   **Memory allocation**: Creating a new array using `slice` can be memory-intensive, especially for very large arrays.
*   **Cache locality**: The order in which elements are accessed can affect performance. For example, if you're accessing elements from the beginning of an array, it's more likely to hit the CPU cache.

**Alternatives**

If you need to remove elements from an array while keeping its size constant, consider these alternatives:

*   **Array.prototype.filter()**: Creates a new array with all elements that pass the test implemented by the provided function.
*   **Array.prototype.map()`: Creates a new array populated with the results of calling a provided function on every element in the original array.
*   **Using a library or framework**: Some libraries, like Lodash, provide optimized implementations for common array operations.

Keep in mind that the best approach depends on your specific use case and performance requirements.

Related benchmarks:

slice VS splice VS shift: who is the fastest to keep constant size v2 (version: 0)

100 long list - not 100k splice and shift win, they mutate list slice loose, it creates a copy of list this time only use numbers, not change to strings

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):