Benchmark: slice vs splice - MeasureThat.net

Script Preparation code:

const arr= [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]

Tests:

slice
const arr= [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20] const result = [ ...arr.slice(0, 10), 99, ...arr.slice(10), ]
loop
const arr= [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20] arr.splice(10, 0, 99);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
loop

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 dive into the world of JavaScript microbenchmarks.

The provided JSON represents two test cases for measuring the performance of slicing vs splicing an array in JavaScript. We'll break down each test case and explore the options being compared, pros and cons, and other considerations.

**Test Case 1: Slice**

In this test case, we have the following benchmark definition:
```javascript
const arr= [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]\r\nconst result = [\r\n  ...arr.slice(0, 10),\r\n  99,\r\n  ...arr.slice(10),\r\n];
```
Here, we're creating an array `arr` with 20 elements and then slicing it into two parts: the first 10 elements and the last 10 elements. We're concatenating these two slices using the spread operator (`...`) to create a new array `result`. The goal is to measure the performance of this specific slicing approach.

**Pros and Cons:**

* Pros:
	+ This method is often considered more readable and maintainable, as it clearly separates the source data from the processed data.
	+ It avoids modifying the original array, which can be beneficial for certain use cases (e.g., preserving the original array's integrity).
* Cons:
	+ Creating two new arrays using `slice()` can lead to higher memory allocation and deallocation overhead compared to other methods.

**Test Case 2: Loop**

In this test case, we have the following benchmark definition:
```javascript
const arr= [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]\r\narr.splice(10, 0, 99);
```
Here, we're creating an array `arr` with 20 elements and then modifying it by inserting a new element at index 10. The `splice()` method is used to achieve this.

**Pros and Cons:**

* Pros:
	+ This method can be faster than the slicing approach, as it only requires a single operation on the original array.
	+ It avoids creating two new arrays, which can reduce memory allocation and deallocation overhead.
* Cons:
	+ Modifying the original array can lead to unintended consequences if not properly validated or tested.
	+ The code may be less readable due to its concise nature.

**Library:**

In both test cases, we're using the built-in `Array.prototype.slice()` method, which is a part of the JavaScript standard library. This method returns a shallow copy of a portion of an array.

**Special JS Feature/Syntax:**

There are no special JavaScript features or syntax used in these benchmark definitions. The focus is on comparing the performance of two different approaches to modifying arrays.

**Other Considerations:**

When writing benchmarks, it's essential to consider factors such as:

* Input size and distribution
* Hardware and software configurations (e.g., CPU architecture, browser version)
* Compiler optimizations and caching effects
* Memory allocation and deallocation overhead

In this case, the benchmark results are available, showing that the loop approach is faster than the slicing approach.

**Alternatives:**

Other methods for modifying arrays include:

* Using `Array.prototype.concat()` or `Array.prototype.push()` to create a new array.
* Utilizing libraries like Lodash or Ramda for array manipulation functions (although these may introduce additional overhead).
* Implementing custom array modification logic using loops and arithmetic operations.

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

Related benchmarks:

slice vs splice (version: 0)

Comparing performance of: slice vs loop

Created: 3 years ago by: Guest

Jump to the latest result

slice

loop

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):