Benchmark: Array concat vs spread operator vs push larger list

Tests:

spread operator
var params = Array(2000000).fill(2); var other = [ ...params, 1 ]
Push
var params = Array(2000000).fill(2); var other = params.push(1);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread operator
Push

Fastest: N/A

Slowest: N/A

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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 benchmark definition and test cases.

**Benchmark Definition:**
The benchmark is designed to compare three approaches for concatenating an array:

1. **Push**: Using the `push()` method to add elements to the end of the array.
2. **Spread Operator (`...`)**: Utilizing the new ES6 spread operator to create a new array by copying and extending the original array.

**Options Compared:**
The benchmark compares the performance of these two methods (Push and Spread Operator) for concatenating an array with a large size (2000000 elements, filled with 2). The Push method involves calling `push()` on the end of the array to add new elements, while the Spread Operator creates a new array by copying the original array's elements and adding a single element (1).

**Pros and Cons:**

* **Push Method:**
	+ Pros:
		- Simple and widely supported.
		- Can be useful for modifying existing arrays.
	+ Cons:
		- Can lead to performance issues when dealing with large arrays, as it requires multiple array allocations and resizing.
* **Spread Operator (`...`):**
	+ Pros:
		- More concise and readable than the Push method.
		- Creates a new array without modifying the original one.
	+ Cons:
		- May incur overhead due to creating a new array copy.

**Library and Special JS Features:**
The benchmark uses no external libraries. However, it does utilize a JavaScript feature introduced in ECMAScript 2018 (ES2018): the spread operator (`...`). The spread operator allows for concise array creation by expanding an existing array or object into a new one.

**Other Considerations:**

* **Array Allocation:** When using the Push method, the browser needs to allocate new memory for each added element. This can lead to increased memory usage and slower performance.
* **Cache Locality:** Modern browsers use various caching mechanisms to improve performance. However, when concatenating arrays using the Push method, the cache locality is disrupted due to the frequent allocation of new memory.

**Alternatives:**
In addition to the two methods being compared in this benchmark, other approaches for array concatenation exist:

* **`concat()` Method:** This is another widely supported method for concatenating arrays. While it may have similar performance characteristics to the Push method, its syntax can be less readable.
* **`array.prototype.reduce()` Method:** Some browsers support using `reduce()` to concatenate arrays. However, this approach often requires more code and can lead to less cache locality.

For a simple array concatenation task, the Spread Operator (`...`) is generally recommended due to its concise syntax and performance benefits.

Related benchmarks:

Array concat vs spread operator vs push larger list (version: 0)

Compare the new ES6 spread operator with the traditional concat() method and push

Comparing performance of: spread operator vs Push

Created: 4 years ago by: Guest

Jump to the latest result

spread operator

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):