Benchmark: Array construct vs array push vs array concat

Tests:

array construct
let a = []; for(let i=0; i <= 1000; i=i+1) { a = [...a, i ]; };
array push
const a = []; for(let i=0; i <= 1000; i = i + 1) { a.push(i); };
array concat
let a = []; for(let i=0; i <= 1000; i = i + 1) { a = a.concat([i]); };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
array construct
array push
array concat

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 10 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36

Browser/OS: Chrome 138 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
array construct	3431.7 Ops/sec
array push	490038.9 Ops/sec
array concat	7859.7 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided benchmark compares three different approaches to construct an array in JavaScript: using `Array.prototype.push()`, `Array.prototype.concat()`, and creating a new array from scratch using spread syntax (`Array.prototype.slice()` is not used, but rather ` [...array, element]`).

**Test Case Comparison**

Each test case measures the performance of one specific approach:

1. **Array Construct**: This test case uses a traditional loop to create an array by pushing elements onto it.
2. **Array Push**: This test case uses the `push()` method to append elements to an existing array.
3. **Array Concat**: This test case uses the `concat()` method to merge arrays and add new elements.

**Options Compared**

The benchmark compares these three approaches, which have different performance characteristics:

* **Array Construct**: Can be slower because it involves a loop and pushing elements onto the array, which can lead to memory reallocations.
* **Array Push**: Typically faster than `Array Construct` because it only involves pushing elements onto an existing array, without the need for loop iterations or memory reallocations.
* **Array Concat**: Often slower than both `Array Construct` and `Array Push`, as it creates a new array by merging existing arrays.

**Pros and Cons of Each Approach**

Here's a brief summary:

* **Array Construct**:
	+ Pros: Simple to implement, easy to understand.
	+ Cons: Can be slow due to loop iterations and memory reallocations.
* **Array Push**:
	+ Pros: Generally fast, efficient use of existing array space.
	+ Cons: Limited control over the resulting array structure.
* **Array Concat**:
	+ Pros: Flexible for merging arrays, but can lead to slower performance.
	+ Cons: Can create a new array with additional memory usage.

**Other Considerations**

When choosing an approach:

* Use `Array Construct` when simplicity and readability are more important than performance.
* Choose `Array Push` when you need to append elements to an existing array frequently, as it tends to be faster.
* Consider using `Array Concat` for merging arrays or adding large amounts of data, but be aware that it may lead to slower performance due to memory reallocations.

**Library and Special Features**

No specific libraries are mentioned in the benchmark definition. However, JavaScript has many other useful features and built-in methods that can affect array operations, such as:

* `Array.prototype.reduce()`
* `Array.prototype.forEach()`
* `Array.prototype.map()`

These methods can provide alternative ways to manipulate arrays, but may have performance implications depending on the specific use case.

**Alternatives**

Other alternatives for constructing or manipulating arrays in JavaScript include:

* Using `Array.from()` to create an array from a iterable source
* Utilizing libraries like Lodash (which provides functions for array manipulation)
* Implementing custom solutions using various data structures and algorithms

Keep in mind that the best approach often depends on specific requirements, performance constraints, and personal coding style.

Related benchmarks:

Array construct vs array push vs array concat (version: 0)

Comparing performance of: array construct vs array push vs array concat

Created: 6 years ago by: Guest

Jump to the latest result

array construct

array push

array concat

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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