Benchmark: _.union VS. indexOf + push

HTML Preparation code:

<script src="https://cdn.jsdelivr.net/lodash/4.17.11/lodash.min.js"></script>

Script Preparation code:

var arr = [];
var add = _.range(100);
add = add.concat(add);

Tests:

_.union
add.forEach(function (item) { arr = _.union(arr, [item]); });
indexOf + push
add.forEach(function (item) { if(arr.indexOf(item) === -1) { arr.push(item); } });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
_.union
indexOf + push

Fastest: N/A

Slowest: N/A

Latest run results:

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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 data and explain what's being tested, compared, and some pros/cons of each approach.

**Benchmark Definition**

The benchmark is testing two approaches for merging arrays: using Lodash's `_.union` function versus concatenating an array and checking for duplicates using `indexOf` and `push`.

**Script Preparation Code**

```javascript
var arr = [];
var add = _.range(100);
add = add.concat(add);
```

This code creates an empty array `arr` and populates it with 100 elements using the `_range` function from Lodash. The `concat` method is used to double the size of the array, creating two identical arrays: `arr` and `add`.

**Html Preparation Code**

```html
<script src="https://cdn.jsdelivr.net/lodash/4.17.11/lodash.min.js"></script>
```

This line includes the Lodash library from a CDN.

**Individual Test Cases**

There are two test cases:

1. **_.union**
```javascript
add.forEach(function (item) {
    arr = _.union(arr, [item]);
});
```
This code uses the `forEach` method to iterate over the elements of `add`. For each element, it calls the `_union` function from Lodash and merges the current array (`arr`) with a new array containing only the current element. The result is assigned back to `arr`.
2. **indexOf + push**
```javascript
add.forEach(function (item) {
    if(arr.indexOf(item) === -1) {
        arr.push(item);
    }
});
```
This code uses the `forEach` method to iterate over the elements of `add`. For each element, it checks if the current array (`arr`) contains the element using `indexOf`. If not found, it pushes the element onto the end of the array.

**What's being compared?**

The benchmark is comparing the performance of these two approaches for merging arrays:

* **_.union**: Using Lodash's `_.union` function to merge arrays.
* **indexOf + push**: Checking if an element exists in the array using `indexOf` and pushing it onto the end if not found.

**Pros and Cons**

1. **_.union**
	* Pros:
		+ More concise and readable code
		+ Lodash provides a robust implementation of union, which can handle many edge cases.
	* Cons:
		+ May incur additional overhead due to function call and object creation.
2. **indexOf + push**
	* Pros:
		+ Simple and straightforward code
		+ Only relies on built-in JavaScript methods, reducing dependencies.
	* Cons:
		+ More verbose code compared to _.union
		+ Performance may degrade for large arrays due to repeated `indexOf` checks.

**Library: Lodash**

Lodash is a popular JavaScript utility library that provides a wide range of functions for various tasks, including array manipulation. In this benchmark, Lodash's `_union` function is used to merge the arrays.

**Special JS feature/Syntax**

None mentioned in the provided code.

**Alternatives**

If you need to perform array merging, consider using modern JavaScript methods like `set`, `add`, or ` concatAll` (if supported by your target browsers). Alternatively, you can implement your own union function using a combination of built-in methods like `indexOf` and `push`.

Keep in mind that the choice of approach depends on your specific use case, performance requirements, and personal preference.

Related benchmarks:

_.union VS. indexOf + push (version: 0)

Comparing performance of: _.union vs indexOf + push

Created: 7 years ago by: Guest

Jump to the latest result

_.union

indexOf + push

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):