Benchmark: Array.prototype.concat vs spread operator

Script Preparation code:

var arr = Array(100).fill([{n: ''}]);

Tests:

Array.prototype.concat
var params = Array(1000).fill([{n: ''}]); var other = arr.concat(params);
spread operator
var params = Array(1000).fill([{n: ''}]); var other = arr.push(...params);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.prototype.concat
spread operator

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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The provided JSON represents a JavaScript microbenchmark that compares two approaches for concatenating arrays: the traditional `Array.prototype.concat()` method and the new ES6 spread operator (`...`).

**What is being tested?**

In this benchmark, two test cases are compared:

1. **Array.prototype.concat()**: This approach uses the `concat()` method to concatenate two arrays.
2. **Spread Operator (`...`)**: This approach uses the spread operator to concatenate two arrays.

The benchmark creates an array `arr` with 100 elements and fills it with objects, then measures how long it takes to concatenate this array with another large array (1,000 times larger) using each of these approaches.

**Options compared**

Two options are being compared:

* **Traditional concat() method**: This is a built-in JavaScript method that concatenates two arrays by creating a new array and adding all elements from both arrays.
* **Spread Operator (`...`)**: This is a new syntax introduced in ES6 that allows for more concise array concatenation. It works by taking the elements of an iterable (such as an array) and spreading them out into the brackets of another iterable.

**Pros and Cons**

**Traditional concat() method**

Pros:

* Well-documented and widely supported
* Easy to understand and implement

Cons:

* Creates a new array, which can be memory-intensive for large datasets
* Can be slower than other approaches due to the overhead of creating a new array

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

Pros:

* More concise and readable
* Does not create a new array, making it more efficient in terms of memory usage
* Is supported by most modern JavaScript engines

Cons:

* May not be as well-documented or widely supported as the traditional `concat()` method
* Can be slower than other approaches due to the overhead of parsing and executing the spread operator syntax

**Library used**

None. This benchmark uses only built-in JavaScript features.

**Special JS feature or syntax**

The spread operator (`...`) is a new syntax introduced in ES6, which allows for more concise array concatenation.

**Other considerations**

* The benchmark measures the performance of each approach using a simple test case with two arrays of different sizes. In real-world scenarios, the performance differences between these approaches may be less pronounced.
* The benchmark does not account for other factors that could affect performance, such as CPU speed, memory availability, or network latency.

**Alternative approaches**

Other alternatives to concatenating arrays include:

* Using `Array.prototype.push()` and iterating over an array of elements
* Using a library like Lodash or Ramda, which provides more efficient and concise ways to concatenate arrays.

Related benchmarks:

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

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

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

Created: 7 years ago by: Guest

Jump to the latest result

Array.prototype.concat

spread operator

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):