Benchmark: js spread vs concat

Tests:

Spread
const arr1 = [ "hello", true, 7 ]; const arr2 = [ "hello", true, 7 ]; function sum(arr){ return arr.reduce((prev, curr) => prev + curr, 0); } sum([...arr1,...arr2]);
Concat
const arr1 = [ "hello", true, 7 ]; const arr2 = [ "hello", true, 7 ]; function sum(arr){ return arr.reduce((prev, curr) => prev + curr, 0); } sum(arr1.concat(arr2));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread
Concat

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 benchmark and explain what's being tested.

**What is being tested?**

The provided JSON represents two test cases for measuring the performance difference between JavaScript's spread operator (`...`) and the `concat()` method when concatenating arrays in a specific scenario. The test case uses a simple function that calculates the sum of all elements in an array using the `reduce()` method.

**Options being compared:**

Two options are being compared:

1. **Spread Operator (`...`)**: This operator creates a new array by spreading the elements of an existing array.
2. **Concat() Method**: This method concatenates two or more arrays into a new array.

**Pros and Cons of each approach:**

* **Spread Operator (`...`)**:
	+ Pros:
		- More concise and readable code
		- Creates a new array, which can be beneficial for performance if the original array is large
	+ Cons:
		- May incur overhead due to creating a new array
		- Can lead to increased memory allocation if not handled properly
* **Concat() Method**:
	+ Pros:
		- Efficient use of existing arrays' memory
		- Often faster due to optimized implementation
	+ Cons:
		- Requires explicit concatenation, which can make code less readable

**Library and purpose:**

None of the provided test cases use any external libraries. The `reduce()` method is a built-in JavaScript method for reducing an array to a single value.

**Special JS feature or syntax:**

The spread operator (`...`) was introduced in ECMAScript 2015 (ES6) and has become a standard feature in modern JavaScript. It provides a concise way to create new arrays by spreading existing arrays.

**Benchmark preparation code:**

The provided benchmark preparation code is empty, which means that the test case relies on the default setup of MeasureThat.net.

**Alternatives:**

Other alternatives for concatenating arrays include:

* Using `Array.prototype.push()` method to add elements to an array
* Using a loop to manually append elements to an array
* Using other libraries or frameworks that provide optimized array concatenation methods (e.g., Lodash)

In general, the choice of concatenation method depends on the specific use case, performance requirements, and code readability preferences.

Related benchmarks:

js spread vs concat (version: 0)

Comparing performance of: Spread vs Concat

Created: 3 years ago by: Guest

Jump to the latest result

Spread

Concat

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):