Benchmark: Lodash _.union vs native Set() with large arrays using spread

HTML Preparation code:

<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/lodash@4.17.10/lodash.min.js"></script>

Script Preparation code:

var a = new Array(1000).map((x,i) => i);
var b = new Array(500).map((x,i) => 500 - i)

Tests:

_.union
var c = _.union(a, b)
Set() spread into array
var c = [...(new Set([...a, ...b]))]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
_.union
Set() spread into array

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36

Browser/OS: Chrome 127 on Mac OS X 10.15.7

View result in a separate tab

Set() spread into array

72K/s

_.union

61K/s

View exact numbers

Test name	Executions per second
✓ Set() spread into array	71,630 Ops/sec
_.union	61,253 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what's being tested in the benchmark.

**Benchmark Definition**

The website uses a JSON object to define the benchmark, which includes:

*   `Name`: A unique name for the benchmark, "Lodash _.union vs native Set() with large arrays using spread".
*   `Description`: An empty string, indicating that no description is provided.
*   `Script Preparation Code` and `Html Preparation Code`: These two sections specify the code that needs to be executed before running the benchmark. The script prepares two large arrays, `a` and `b`, using array destructuring and map functions. The HTML preparation code includes a link to load the Lodash library.

**Individual Test Cases**

The benchmark consists of two individual test cases:

1.  **Test Case 1: `_` union**
    *   **Benchmark Definition**: `var c = _.union(a, b)`.
    *   **Purpose**: This test case measures the performance of the `_.union()` function from Lodash when used to merge two large arrays.
2.  **Test Case 2: Native Set() with spread**
    *   **Benchmark Definition**: `var c = [...(new Set([...a, ...b]))]`.
    *   **Purpose**: This test case measures the performance of merging two large arrays using the native `Set()` function and array spread operator.

**Comparison of Approaches**

The benchmark compares the performance of two approaches:

1.  **Lodash _.union()**: The first approach uses the `_` union function from Lodash to merge the two arrays.
2.  **Native Set() with array spread**: The second approach uses the native `Set()` function and array spread operator (`...`) to merge the two arrays.

**Pros and Cons of Each Approach**

Here are some pros and cons for each approach:

*   **Lodash _.union()**:
    *   Pros:
        *   Easier to read and maintain, as it's a well-documented and tested function.
        *   May be faster due to potential optimizations within the Lodash library.
    *   Cons:
        *   May introduce unnecessary overhead due to the additional function call and argument passing.
*   **Native Set() with array spread**:
    *   Pros:
        *   Lightweight, as it only uses built-in JavaScript functions.
        *   Can be faster in some cases due to optimized native code.
    *   Cons:
        *   May have a steeper learning curve due to the use of new syntax and features.

**Library: Lodash**

Lodash is a popular JavaScript utility library that provides various functions for tasks such as array manipulation, object transformation, and more. The `_` union function in this benchmark is used to merge two arrays, eliminating duplicates while preserving order.

The test case uses the latest version of Lodash (4.17.10) available on CDN.

**Special JS Feature/Syntax**

This benchmark does not use any special JavaScript features or syntax that would require additional explanation. However, it's worth noting that the array spread operator (`...`) and native `Set()` function are relatively new features introduced in ECMAScript 2015 (ES6) and later versions.

**Alternatives**

If you're looking for alternatives to benchmarking JavaScript performance, consider:

1.  **V8 Benchmark Suite**: A comprehensive set of benchmarks developed by Google's V8 engine team.
2.  **JSPerf**: A popular benchmarking tool that allows running multiple tests in a single execution.
3.  **BenchmarkDotNet**: An open-source benchmarking library for .NET languages, including JavaScript.

These tools can help you compare performance across different browsers, environments, and approaches, ensuring optimal execution times for your applications.

Lodash _.union vs native Set() with large arrays using spread (version: 0)

Comparing performance of: `_.union vs Set() spread into array`

Created: one year ago by: Guest

Go to the latest result

_.union

Set() spread into array

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

Lodash _.union vs native Set() with large arrays using spread (version: 0)

Comparing performance of: _.union vs Set() spread into array

Created: one year ago by: Guest

Go to the latest result

_.union

Set() spread into array

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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Comparing performance of: `_.union vs Set() spread into array`