Benchmark: Shift performance

Script Preparation code:

var list = [];
for (var i = 0; i < 500; i++) {
  list.push(i);
}

Tests:

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

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 explain what's being tested.

**Overview**

The benchmark tests the performance of three different approaches to remove an element from the end of an array in JavaScript: `slice`, `splice`, and `shift`. The test is designed to measure which approach is the fastest.

**Test Case 1: "slice"**

* **Benchmark Definition**: `list.push('slice');\r\nlist = list.slice(1);`
	+ This test creates an array, pushes a string 'slice' onto it, and then uses the `slice` method to remove the first element (i.e., the last added one).
* **Purpose**: To measure the performance of creating a copy of the array using the `slice` method.
* **Pros**: Fast and efficient, as it creates a new array without modifying the original one.
* **Cons**: Creates an unnecessary copy of the array, which can be memory-intensive for large arrays.

**Test Case 2: "splice"**

* **Benchmark Definition**: `list.push('splice');\r\nlist.splice(0, 1);`
	+ This test creates an array, pushes a string 'splice' onto it, and then uses the `splice` method to remove the first element.
* **Purpose**: To measure the performance of modifying the original array in place using the `splice` method.
* **Pros**: Modifies the original array without creating a copy, which can be more memory-efficient for large arrays.
* **Cons**: Can be slower than other approaches due to its complexity.

**Test Case 3: "shift"**

* **Benchmark Definition**: `list.push('shift');\r\nlist.shift();`
	+ This test creates an array, pushes a string 'shift' onto it, and then uses the `shift` method to remove the first element.
* **Purpose**: To measure the performance of removing the first element from the original array using the `shift` method.
* **Pros**: Simple and efficient, as it modifies the original array in place without creating a copy.
* **Cons**: Only suitable for arrays with at least one element, as it would throw an error otherwise.

**Library Used**

None is explicitly mentioned in the provided benchmark code. However, it's likely that the JavaScript engine being tested supports the built-in `slice`, `splice`, and `shift` methods, which are part of the ECMAScript standard.

**Special JS Feature or Syntax**

There is no mention of any special JavaScript features or syntax in the provided benchmark code.

**Other Alternatives**

Other approaches to remove an element from the end of an array in JavaScript include:

1. Using a library like Lodash's `rest` function, which returns a new array with all elements except the first one.
2. Using the `concat()` method to create a new array with the remaining elements.
3. Creating a new array and iterating over the original array using `forEach` or a similar method.

However, these alternatives are not included in this benchmark, as they were not specified in the provided benchmark definition.

**Benchmark Result Interpretation**

The latest benchmark result shows that:

1. The `shift` approach is the fastest, followed by `slice`, and then `splice`.
2. Chrome 91 on a desktop platform performs better than slice and splice.
3. Executions per second are higher for shift, indicating it's faster.

Keep in mind that this analysis assumes that the benchmark code is correct and accurate. In reality, there might be other factors affecting the performance of these approaches, such as memory allocation, caching, or specific browser optimizations.

Related benchmarks:

Shift performance (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):