Benchmark: join with spread vs concat

Script Preparation code:

var a = ['a',1,true];
var b = ['b',2,false];

Tests:

concat
const c = a.concat(b);
spread
const c = [...a, ...b]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
concat
spread

Fastest: N/A

Slowest: N/A

Latest run results:

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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 and explain what's being tested.

**Benchmark Overview**

The benchmark is comparing two approaches to concatenate arrays in JavaScript: using the `concat()` method versus using the spread operator (`...`). The test case consists of two individual tests: "concat" and "spread".

**What are we testing?**

We're testing how fast each approach is when concatenating two arrays. In this specific benchmark, the arrays `a` and `b` contain three elements each.

**Options Compared**

There are two options being compared:

1. **`concat()` method**: This is a built-in JavaScript method that concatenates two or more arrays.
2. **Spread operator (`...`)**: This is a relatively new feature in JavaScript introduced in ES6, which allows you to expand an array into separate arguments.

**Pros and Cons of Each Approach**

**`concat()` method:**

Pros:

* Widely supported across different browsers and versions
* Easy to understand and use
* Works with older browsers that don't support the spread operator

Cons:

* Can be slower than the spread operator, especially for large arrays
* Creates a new array, which can lead to performance issues in certain scenarios

**Spread operator (`...`)**

Pros:

* Faster than `concat()` method, especially for large arrays
* Creates a new array with fewer copies of data, resulting in less memory usage

Cons:

* Requires modern browsers and JavaScript versions (ES6+)
* Can be less readable or intuitive for some developers

**Library Usage**

None.

**Special JS Feature/Syntax**

The spread operator (`...`) is the special feature used in this benchmark. It was introduced in ES6 as a concise way to expand an array into separate arguments.

**Other Considerations**

When choosing between `concat()` and the spread operator, consider the following:

* If you need to support older browsers or require a more traditional approach, use the `concat()` method.
* If you're targeting modern browsers and want to write more concise code, use the spread operator.

**Alternative Approaches**

Other ways to concatenate arrays in JavaScript include:

1. Using array methods like `push()`, `unshift()`, etc., which can be less efficient than using `concat()` or the spread operator.
2. Using libraries like Lodash, which provides an `flatten()` method for concatenating arrays.
3. Using a loop to concatenate elements manually.

Keep in mind that the choice of approach depends on your specific use case, performance requirements, and personal preference.

Related benchmarks:

join with spread vs concat (version: 0)

Comparing performance of: concat vs spread

Created: 5 years ago by: Guest

Jump to the latest result

concat

spread

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):