Benchmark: concatenating 2 arrays

Tests:

push apply
var arr = [1,2,3,4,5,6,7,8,9,10] var arr2 = [] Array.prototype.push.apply(arr2, arr)
push spread
var arr = [1,2,3,4,5,6,7,8,9,10] var arr2 = [] arr2.push(...arr)
concat
var arr = [1,2,3,4,5,6,7,8,9,10] var arr2 = [] arr2 = arr2.concat(arr)
for push
var arr = [1,2,3,4,5,6,7,8,9,10] var arr2 = [] for(var i = 0, len = arr.length; i < len; i++) { arr2.push(arr[i]) }
for of push
var arr = [1,2,3,4,5,6,7,8,9,10] var arr2 = [] for(var item of arr) { arr2.push(item) }
forEach push
var arr = [1,2,3,4,5,6,7,8,9,10] var arr2 = [] arr.forEach(function(item) { arr2.push(item) })

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
push apply
push spread
concat
for push
for of push
forEach push

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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I'd be happy to explain what's being tested in the provided JSON.

**Benchmark Definition**

The benchmark definition represents a JavaScript operation that concatenates two arrays. The operation is defined as follows:

* Two arrays, `arr` and `arr2`, are created with different methods:
	+ Some tests use `Array.prototype.push.apply(arr2, arr)`.
	+ Some tests use the spread operator (`...`) to concatenate the arrays: `arr2.push(...arr)`.
	+ Some tests use the `concat()` method to concatenate the arrays: `arr2 = arr2.concat(arr)`.
	+ Two tests use a `for` loop with array iteration: `for(var i = 0, len = arr.length; i < len; i++) {arr2.push(arr[i])}` and `for(var item of arr) {arr2.push(item)}`.
* The test measures the execution time for each method.

**Options Compared**

The benchmark compares four different methods to concatenate two arrays:

1. **`Array.prototype.push.apply()`**: This method applies an array function to all elements of the original array, in this case, `push()` to the second array.
2. **Spread operator (`...`)**: This method uses the spread operator to expand the first array and push its elements onto the second array.
3. **`concat()` method**: This method creates a new array by concatenating the two input arrays.
4. **`for` loop with array iteration**: Two tests use a `for` loop to iterate over each element of the first array and push it onto the second array.

**Pros and Cons**

Each method has its own trade-offs:

* **`Array.prototype.push.apply()`**: Fast, but can be slower for large arrays due to the overhead of function application.
* **Spread operator (`...`)**: Concise and expressive, but may incur a small performance penalty due to the creation of temporary arrays.
* **`concat()` method**: Straightforward and easy to read, but creates a new array, which can lead to increased memory usage.
* **`for` loop with array iteration**: Control over the iteration process, but can be slower and more verbose than other methods.

**Other Considerations**

* The benchmark assumes that the input arrays have the same length. If the arrays are of different lengths, the results may vary depending on which method is used.
* The benchmark does not account for potential side effects or modifications to the original arrays during the concatenation process.

**Alternative Approaches**

Other alternatives to concatenate two arrays in JavaScript include:

* Using `Array.prototype.reduce()` with an accumulator function
* Using a library like Lodash's `concat` function
* Implementing custom concatenation functions, such as using a linked list or other data structure

Keep in mind that these alternative approaches may have different performance characteristics and trade-offs compared to the methods tested in this benchmark.

Related benchmarks:

concatenating 2 arrays (version: 0)

Comparing performance of: push apply vs push spread vs concat vs for push vs for of push vs forEach push

Created: 3 years ago by: Guest

Jump to the latest result

push apply

push spread

concat

for push

for of push

forEach push

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):