Benchmark: spread vs push 2

Tests:

spread
const arr = [...new Array(30)].map((v, i) => i); const result = [...arr, 30];
push
const arr = [...new Array(30)].map((v, i) => i); const result = arr.push(30);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread
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 benchmark and its results.

**Benchmark Definition**

The benchmark measures the performance difference between using `Array.prototype.push()` and the spread operator (`...`) to add an element to an array.

**Test Cases**

There are two test cases:

1. **Spread**: The script creates an array with 30 elements, maps over it to create a new array with the index as the value, and then spreads this new array into another array, adding 30 at the end.
2. **Push**: The script is similar to the spread case, but instead of using the spread operator, it uses `Array.prototype.push()` to add the element.

**Library Used**

In both test cases, the `[...new Array(30)]` expression is used, which is a common idiom in JavaScript for creating an array with a specified number of elements. This is known as the "array literal" or "constructor function" syntax. It creates a new array by cloning the prototype chain of `Array.prototype`, and then using `new Array(30)` to create 30 elements.

**Special JS Feature/ Syntax**

There's no specific JavaScript feature or syntax being used in these test cases, but it's worth noting that the spread operator (`...`) was introduced in ECMAScript 2015 (ES6) as a way to create new arrays by spreading existing ones. The `push()` method has been available since ES5.

**Options Compared**

The two options being compared are:

* **Spread Operator (`...`)**: Creates a new array by cloning the elements of an existing array.
* **Push() Method**: Adds one or more elements to the end of an array.

**Pros and Cons of Each Approach**

**Spread Operator (`...`)**

Pros:

* Creates a shallow copy of the original array, which can be faster for large arrays since it only allocates memory for the new elements.
* Can be used to create new arrays with specific properties or behaviors (e.g., using `Object.assign()`).

Cons:

* Can be slower than `push()` for very small arrays or when the underlying array is nearly full.
* Requires a separate allocation of memory for each element, which can lead to more garbage collection.

**Push() Method**

Pros:

* Faster than the spread operator for very small arrays or when the underlying array is nearly full.
* Does not require a separate allocation of memory for each element.

Cons:

* Creates a deep copy of the original array, which can be slower and use more memory.
* Can lead to performance issues if the underlying array is large or has many elements.

**Other Considerations**

When choosing between these two approaches, consider the following factors:

* The size of the arrays being operated on. For small arrays, `push()` might be faster.
* The properties or behavior required for the new array. If you need to preserve specific properties or behaviors, the spread operator (`...`) might be a better choice.
* Memory constraints. If memory is limited, using the push() method can help reduce allocation overhead.

**Alternatives**

Other alternatives to compare when benchmarking array operations include:

* Using `Array.prototype.concat()` instead of the spread operator (`...`).
* Comparing the performance of other methods for adding elements to an array, such as `Array.prototype splice()` or `Array.prototype unshift()`.

Related benchmarks:

spread vs push 2 (version: 0)

Comparing performance of: spread vs push

Created: 5 years ago by: Guest

Jump to the latest result

spread

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):