Benchmark: Array.prototype.concat vs spread operator vs stringify

Script Preparation code:

var array1 = Array(400).fill().map(() => Math.round(Math.random() * 40));
var array2 = Array(400).fill().map(() => Math.round(Math.random() * 40));

Tests:

Array.prototype.concat
var others = array1.concat(array2);
spread operator
var others = [...array1, ...array2];
stringify
var others = JSON.parse((JSON.stringify(array1)+JSON.stringify(array2)).replace('][',','))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.prototype.concat
spread operator
stringify

Fastest: N/A

Slowest: N/A

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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 JSON and explain what's being tested, compared, and their pros and cons.

**Benchmark Definition**

The benchmark compares three approaches to concatenate two arrays:

1. **Array.prototype.concat()**: A traditional method for concatenating arrays in JavaScript.
2. **Spread Operator (`...`)**: The new ES6 spread operator introduced in ECMAScript 2015, which allows using the `...` syntax to expand an array into individual elements.
3. **JSON.stringify() and JSON.parse()**: A workaround that involves converting the array to a string using `JSON.stringify()` and then parsing it back to an array using `JSON.parse()`.

**Script Preparation Code**

The script preparation code creates two large arrays, each with 400 random integers between 0 and 40. These arrays will be concatenated or modified in different ways for each test case.

**Html Preparation Code**

There is no HTML preparation code provided, which means the benchmark is a simple JavaScript performance comparison without any GUI-related overhead.

**Individual Test Cases**

The three test cases are:

1. **Array.prototype.concat**: Concatenates `array1` and `array2` using the traditional `concat()` method.
2. **Spread Operator**: Expands `array1` and `array2` into individual elements using the spread operator (`...`) and then concatenates them.
3. **stringify**: Converts both arrays to strings using `JSON.stringify()`, combines them, replaces `]` with `,`, and then parses the resulting string back to an array.

**Library**

None of these test cases rely on a specific JavaScript library.

**Special JS Feature/Syntax**

The spread operator (`...`) is a new feature introduced in ECMAScript 2015. It's used to expand arrays into individual elements, allowing for more concise and expressive code.

**Pros and Cons of Each Approach**

Here's a brief summary:

* **Array.prototype.concat()**: This traditional method works well for small to medium-sized arrays but can be slow for large datasets due to the overhead of creating a new array object. Pros: easy to understand and implement, widely supported. Cons: performance-intensive for large arrays.
* **Spread Operator (`...`)**: This new feature is more efficient than `concat()` for large arrays, as it avoids the overhead of creating a new array object. However, its support was not universal until ECMAScript 2015, so older browsers might not execute this test case. Pros: faster performance, concise syntax. Cons: requires modern JavaScript versions.
* **JSON.stringify() and JSON.parse()**: This workaround involves converting arrays to strings, which can be slower than using the spread operator or `concat()` for large datasets. However, it's a viable option when working with legacy browsers that don't support the spread operator or older versions of ECMAScript. Pros: works on older browsers, provides an alternative solution. Cons: slower performance compared to other methods.

**Alternatives**

Other alternatives to measure array concatenation performance might include:

* Using `Array.prototype.push()` instead of `concat()`
* Comparing the performance of different libraries or frameworks that handle array concatenation (e.g., React's `concat` method)
* Measuring the performance of other data structures, such as linked lists or tree-based data structures

Related benchmarks:

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

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

Comparing performance of: Array.prototype.concat vs spread operator vs stringify

Created: 8 years ago by: Guest

Jump to the latest result

Array.prototype.concat

spread operator

stringify

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):