Benchmark: In place array concatenation benchmark.

Tests:

Spread Operator
var arr1 = [1,2,3]; var arr2 = [4,5,6]; arr1.push(...arr2);
Push Apply
var arr1 = [1,2,3]; var arr2 = [4,5,6]; arr1.push.apply(arr1, arr2);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread Operator
Push Apply

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 years ago)

User agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36

Browser/OS: Chrome 62 on Windows 8.1

View result in a separate tab

Test name	Executions per second
Spread Operator	16510253.0 Ops/sec
Push Apply	15844048.0 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 provided benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark is designed to compare the performance of two approaches for concatenating arrays in JavaScript: the spread operator (`...`) and `push.apply()`.

**Options Compared**

Two options are compared:

1. **Spread Operator**: This approach uses the `...` operator to expand the array `arr2` into separate arguments, which are then pushed onto `arr1`.
2. **Push Apply**: This approach uses the `apply()` method of the `push()` function to pass `arr2` as an array of arguments to be executed by `push()`.

**Pros and Cons**

* **Spread Operator**
	+ Pros: More concise, easier to read, and often faster due to optimized JavaScript engine implementations.
	+ Cons: May not work in older browsers or environments that don't support the spread operator (e.g., Internet Explorer 11).
* **Push Apply**
	+ Pros: Works in all modern browsers and environments, including older ones.
	+ Cons: Less concise, harder to read, and may be slower due to the overhead of `apply()`.

**Library Used**

None. This benchmark is a simple JavaScript microbenchmark that uses built-in JavaScript features.

**Special JS Feature or Syntax**

The spread operator (`...`) was introduced in ECMAScript 2015 (ES6) and has since become a standard feature in modern browsers. It's used to expand arrays into separate arguments, allowing for more concise and readable code.

**Other Alternatives**

If you need to concatenate arrays in JavaScript before a certain version of ES6, you might consider using the following alternatives:

* `concat()`: This method concatenates two or more arrays and returns a new array. It's less efficient than the spread operator but works in older browsers.
* Array.prototype.push.call(): This approach uses the `call()` method to pass an array of arguments to `push()`, similar to `apply()`. However, it's less concise and harder to read.

In summary, if you need to concatenate arrays in JavaScript, the spread operator is often a good choice due to its conciseness and potential performance benefits. If you need to support older browsers or environments, you may need to use an alternative approach like `concat()` or `push.call()`.

Related benchmarks:

In place array concatenation benchmark. (version: 2)

Test performance between spread operator and push.apply

Comparing performance of: Spread Operator vs Push Apply

Created: 7 years ago by: Registered User

Jump to the latest result

Spread Operator

Push Apply

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):