Benchmark: Array.prototype.concat vs spread operator

Tests:

slice
var other = [ "hello", true, 7 ].concat([ 1, 2, 3]);
spread operator
var other = [ ...[ "hello", true, 7 ], ...[ 1, 2, 3] ]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
spread operator

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36

Browser/OS: Chrome 130 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
slice	17007744.0 Ops/sec
spread operator	44220176.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The test is comparing two approaches to concatenate arrays in JavaScript:

1. The traditional `concat()` method.
2. The new ES6 spread operator (`...`).

**Options Compared**

In this benchmark, we have two options:

1. **Concatenation using the traditional `concat()` method**: This approach uses the built-in `concat()` function to merge two arrays.
2. **Concatenation using the spread operator**: This approach uses the new ES6 spread operator (`...`) to merge two arrays.

**Pros and Cons of Each Approach**

**Traditional `concat()` Method:**

Pros:

* Widely supported across browsers and JavaScript engines.
* Well-established and understood by developers.

Cons:

* Can be slower than the spread operator due to the overhead of function calls.
* May incur additional memory allocations.

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

Pros:

* Faster execution compared to `concat()`.
* Reduces memory allocations since it uses a new array to store the merged elements.

Cons:

* Requires modern JavaScript engines and browsers that support the ES6 spread operator.
* Syntax may be unfamiliar to some developers.

**Library and Special JS Feature**

In this benchmark, we don't see any libraries being used. However, the use of the spread operator is a special JavaScript feature introduced in ECMAScript 2015 (ES6).

**Other Considerations**

When choosing between these two approaches, consider the following:

* Performance: If you need to concatenate large arrays frequently, the spread operator might be a better choice due to its potential speed advantages.
* Browser Support: Ensure that your target browsers support the ES6 spread operator. Older browsers or those without native support may require polyfills or workarounds.

**Alternative Approaches**

Other alternatives for concatenating arrays in JavaScript include:

1. `Array.prototype.push()`: This approach uses the `push()` method to add elements to an array, but it's less efficient than the spread operator.
2. `Array.prototype.splice()`: This approach uses the `splice()` method to remove and replace elements in an array, which can be slower and more memory-intensive than the spread operator.

Overall, the choice between the traditional `concat()` method and the spread operator depends on your specific use case, performance requirements, and target browser support.

Related benchmarks:

Array.prototype.concat vs spread operator (version: 0)

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

Comparing performance of: slice vs spread operator

Created: 8 years ago by: Guest

Jump to the latest result

slice

spread operator

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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