Benchmark: Splice vs Spread vs Unshift vs Concat to insert at beginning of array (fixed from slice)

Script Preparation code:

var array = Array.from({ length: 100 }).map((val, i) => i);

Tests:

Splice
var newArray = array.splice(0, 0, 99);
Spread
var newArray = [99, ...array];
Unshift
var newArray = array.unshift(99);
Concat
var newArray = [99].concat(array);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Splice
Spread
Unshift
Concat

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 break down the provided JSON and explain what is being tested, compared, and analyzed.

**Benchmark Definition**
The benchmark is designed to compare four different methods for inserting an element at the beginning of an array: `splice`, `spread`, `unshift`, and `concat`. The tests are focused on measuring which method is the fastest.

**Options Compared**

1. **Splice**: This method modifies the original array by removing elements from a specified index, then inserts the new element at that position.
2. **Spread**: This method uses the spread operator (`...`) to create a new array with the spread operator applied to the existing array. It then spreads the elements of another array into the resulting array using the spread operator again.
3. **Unshift**: This method modifies the original array by adding an element at the beginning of the array using the `unshift` method.
4. **Concat**: This method creates a new array by concatenating two arrays: the original array and a new array with the single element to be inserted.

**Pros and Cons of Each Approach**

1. **Splice**:
	* Pros: Can modify the original array, can handle large arrays efficiently.
	* Cons: Modifies the original array, which may not be desirable for some use cases.
2. **Spread**:
	* Pros: Creates a new array, preserves the original array's integrity, efficient for large arrays.
	* Cons: Requires two spread operations, can be slower than other methods.
3. **Unshift**:
	* Pros: Modifies the original array, fast execution time, easy to understand.
	* Cons: May not be suitable for very large arrays due to memory constraints.
4. **Concat**:
	* Pros: Creates a new array, easy to understand, can handle large arrays efficiently.
	* Cons: Requires creating two separate arrays, which can lead to increased memory usage.

**Library Usage**
None of the test cases use any external libraries.

**Special JavaScript Features/Syntax**
The tests use modern JavaScript features such as:

1. **Spread Operator (`...`)**: Used in the `spread` and `concat` methods.
2. **Rest Parameter Syntax (`var [99, ...array]`)**: Used in the `spread` method.
3. **Arrow Function (`=> i`)**: Used in the script preparation code to create an array of numbers.

**Other Alternatives**
If the tests were designed for other platforms or browsers, alternative methods might be considered:

1. For mobile devices: `push` instead of `unshift`, or using a library like jQuery Mobile.
2. For older browsers (e.g., Internet Explorer 9+): Using polyfills or workarounds to support modern features.

Note that the specific alternatives will depend on the target platform and browser versions being tested.

Related benchmarks:

Splice vs Spread vs Unshift vs Concat to insert at beginning of array (fixed from slice) (version: 0)

Comparing performance of: Splice vs Spread vs Unshift vs Concat

Created: 3 years ago by: Guest

Jump to the latest result

Splice

Spread

Unshift

Concat

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):