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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Let's dive into explaining the benchmark and its test cases.

**Benchmark Overview**

MeasureThat.net is used to compare different JavaScript approaches for array concatenation. The provided JSON defines two benchmark test cases: `Array.prototype.concat` and `spread operator`. The goal is to measure which approach performs better in terms of execution speed, given a large dataset.

**Options Compared**

The two options being compared are:

1. **`Array.prototype.concat()`**: This is the traditional method for concatenating arrays in JavaScript. It creates a new array by copying elements from the original array and then adds the elements from the second array.
2. **Spread Operator (`...`)**: This is the newer, more modern approach introduced in ES6 (ECMAScript 2015). It allows you to expand an array into multiple arguments or spread its elements across multiple variables.

**Pros and Cons of Each Approach**

**`Array.prototype.concat()`**:

Pros:

* Well-established method with a large user base.
* Can be easily understood by new developers.
* Works in older JavaScript environments (pre-ES6).

Cons:

* Creates a new array, which can lead to memory allocations and potential performance issues for large datasets.

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

Pros:

* More efficient than `concat()` since it only creates a single new array reference.
* Can be faster because it avoids the overhead of creating multiple arrays.
* More concise and easier to read, especially when working with large datasets.

Cons:

* Less widely supported by older JavaScript environments (pre-ES6).
* May not work as expected in some browsers or environments that don't support the spread operator.

**Library Usage**

In this benchmark, no external libraries are used. Both `Array.prototype.concat()` and the spread operator rely on built-in JavaScript functionality.

**Special JS Features/Syntax**

The spread operator (`...`) is a relatively new feature introduced in ES6 (ECMAScript 2015). It allows you to expand an array into multiple arguments or spread its elements across multiple variables. The syntax `arr.push(...params)` uses this feature to add all elements from the `params` array to the existing `arr` array.

**Other Alternatives**

If not using the spread operator, other alternatives for concatenating arrays include:

* `Array.prototype.push()`: Similar to `concat()`, but it modifies the original array.
* `Array.prototype.splice()`: Can be used to concatenate two arrays by using the `push()` method in a loop.

However, these methods are generally less efficient and more cumbersome than using the spread operator or `concat()`.

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):