Benchmark: Concat Vs Spread [eungwang3]

Script Preparation code:

var firstArray = Array.from({length : 5}, (v,i) => ({id : i, name : `firstArray${i}`}))
var secondArray = Array.from({length : 5}, (v,i) => ({id : i, name : `secondArray${i}`}))

Tests:

concat
return firstArray.concat(secondArray);
spread
return [...firstArray,secondArray];

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 benchmark and its test cases.

**Benchmark Definition**

The benchmark is called "Concat Vs Spread" and it tests two different approaches to concatenate two arrays in JavaScript: using the `concat()` method and using the spread operator (`...`).

**Script Preparation Code**

The script preparation code generates two arrays, `firstArray` and `secondArray`, with 5 elements each. Each element is an object with two properties: `id` and `name`. The `name` property uses template literals to generate a string that includes the array index.

**Html Preparation Code**

There is no HTML preparation code provided.

**Test Cases**

The benchmark consists of two test cases:

1. **concat**: This test case measures the performance of concatenating two arrays using the `concat()` method.
2. **spread**: This test case measures the performance of concatenating two arrays using the spread operator (`...`).

**Library and Purpose**

There is no external library used in this benchmark.

**Special JS Feature or Syntax**

The benchmark uses a modern JavaScript feature: template literals (the syntax inside the backticks `` ` ``). Template literals are a feature introduced in ECMAScript 2015, which allows you to create strings with expressions inside them. In this case, they are used to generate the string for the `name` property of each object in the arrays.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

1. **concat()**: This method is more straightforward and easy to read, but it can be slower than the spread operator because it creates a new array by concatenating the elements.
2. **Spread Operator (`...`)**: This method is often faster and more memory-efficient than `concat()` because it avoids creating a new array by concatenating elements.

**Other Considerations**

* The benchmark uses a desktop browser (Chrome 108) on a Mac OS X system, which may not be representative of other platforms.
* The test case assumes that the arrays are large enough to trigger significant performance differences between the two approaches. If the arrays are small, the difference may be negligible.
* There is no consideration for other factors that could affect performance, such as caching, garbage collection, or other concurrent operations.

**Alternatives**

Other alternatives to consider when concatenating arrays include:

1. **Array.prototype.reduce()**: Instead of using `concat()` or the spread operator, you can use the `reduce()` method to concatenate the elements.
2. **Array.prototype.push()**: You can also use `push()` to add elements to an array and then return the new array.

However, these alternatives may have different performance characteristics depending on the specific use case and requirements.

Related benchmarks:

Concat Vs Spread [eungwang3] (version: 0)

Comparing performance of: concat vs spread

Created: 3 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):