Benchmark: Push array 0 index with splice and spread

Tests:

splice insertion
let arr = [1,2,3]; arr.splice(0,0,4);
spread insertion
let arr = [1,2,3]; let newArr = [...arr, 4];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
splice insertion
spread insertion

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36 OPR/63.0.3368.71

Browser/OS: Opera 63 on Windows

View result in a separate tab

Test name	Executions per second
splice insertion	13523789.0 Ops/sec
spread insertion	25166582.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):

LLMs can make mistakes. Check important info.

Measuring the performance of JavaScript microbenchmarks can be fascinating, and it's great that you're interested in understanding what's being tested.

**What is being tested?**

The provided benchmark tests two different approaches for inserting an element into an array:

1. **splice() insertion**: This method modifies the original array by removing the specified number of elements from the beginning (in this case, 0) and then inserts a new element at that position.
2. **Spread insertion** (`...arr, 4`): This method creates a new array by spreading the existing array and then appending the new element.

**Options comparison**

The two approaches have different pros and cons:

*   **Splice() insertion**: This approach is more efficient when inserting elements at the beginning of an array because it modifies the original array. However, it can be slower for large arrays because it requires shifting all subsequent elements to fill the gap.
*   **Spread insertion** (`...arr, 4`): This approach creates a new array without modifying the original array. It is more efficient for large arrays and avoids potential performance issues with shifting elements.

**Library usage**

In this benchmark, there doesn't appear to be any specific JavaScript library being used. However, some browsers like Opera might have their own implementation of certain functions (e.g., `Array.prototype.splice()` or spread syntax) that might affect the results.

**Special JS features or syntax**

The benchmark does not use any special JavaScript features or syntax beyond what's standard in modern browsers.

**Other alternatives**

Alternative approaches to inserting elements into an array could include:

*   Using `concat()`, which also creates a new array but can be slower than spread insertion for large arrays.
*   Using `Array.prototype.push()` and then using `shift()` to remove the element, although this is less efficient than both splice insertion and spread insertion.

Here's some sample code that demonstrates these alternatives:

```javascript
// Splice() insertion
let arr = [1, 2, 3];
arr.splice(0, 0, 4); // More efficient for small arrays

// Spread insertion
let newArr = [...arr, 4]; // Creates a new array without modifying the original

// Concat()
let arr2 = [1, 2, 3];
let newArr2 = arr2.concat([4]); // Creates a new array but can be slower than spread insertion for large arrays

// Push() and shift()
let arr3 = [1, 2, 3];
arr3.push(4);
while (arr3.length > 0) {
    arr3.shift(); // Less efficient than both splice insertion and spread insertion
}
```

Related benchmarks:

Push array 0 index with splice and spread (version: 0)

Comparing performance of: splice insertion vs spread insertion

Created: 5 years ago by: Guest

Jump to the latest result

splice insertion

spread insertion

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):