Benchmark: spread vs push large

Tests:

Push
const items = new Array(1000); items.push('a');
Spread
let items = new Array(1000); items = [...items, 'a'];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Push
Spread

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 19 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Push	895064.8 Ops/sec
Spread	500884.8 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the JavaScript microbenchmarking test case you provided.

**What is being tested?**

The benchmark compares two approaches to add an element to an array of 1000 elements: using the `push()` method and using the spread operator (`...`). The goal is to determine which approach is faster in modern browsers.

**Options compared:**

* **`push()`**: This method appends a new value to the end of the array. It's a built-in JavaScript method that modifies the original array.
* **Spread operator (`...`)**: This operator creates a new array by copying elements from an existing array and adding a new element.

**Pros and Cons:**

* **`push()`**:
	+ Pros: Modifies the original array, which can be beneficial for arrays that need to grow dynamically. It's also a widely supported method.
	+ Cons: Creates a new copy of the entire array when using `push()`, which can lead to performance issues if the array is large and needs to be frequently updated. Additionally, it requires an extra operation (i.e., the assignment of the result) at the end.
* **Spread operator (`...`)**:
	+ Pros: Creates a new copy of only the changed elements, reducing memory allocation and copying overhead. It's also concise and readable.
	+ Cons: Creates a new array every time it's used, which can lead to higher memory usage if not properly managed. Additionally, it may not be supported in older browsers or versions.

**Other considerations:**

* **Array performance**: In general, pushing elements onto an array is faster than using the spread operator for large arrays, as it avoids creating a new copy of the entire array.
* **Browser support**: The spread operator has been widely adopted by modern browsers, including Chrome 93. However, older versions or other browsers might not support this feature.

**Library and special JS features used:**

None in this specific benchmark. It only uses built-in JavaScript methods (`push()` and `...`).

**Special JS features mentioned:**

None explicitly mentioned. If the benchmark used more advanced JavaScript features like async/await, destructuring, or arrow functions, they would be relevant here.

Now, let's discuss alternatives to this benchmark:

* **Other array push methods**: There are other ways to push elements onto an array, such as using `unshift()` (which adds elements to the beginning of the array) or modifying a specific element.
* **Alternative spread operators**: Other spread operators exist, like the `...` operator used in destructuring (`[a, b] = [1, 2];`) and the spread operator used in arrays with multiple elements (`new Array(3).fill(1).map((x) => x + 1);`).
* **Custom array implementations**: Custom array implementations might offer better performance or specific features for certain use cases.

These alternatives would be relevant when exploring more advanced JavaScript topics, but the `push()` vs. spread operator benchmark is a fundamental example of comparing common array operations in modern JavaScript.

Related benchmarks:

spread vs push large (version: 0)

large

Comparing performance of: Push vs Spread

Created: 3 years ago by: Guest

Jump to the latest result

Push

Spread

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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