Benchmark: Array immutable union: lodash union vs object.assign vs unique

HTML Preparation code:


<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js'></script>

Tests:

lodash union
var a = [ 'a', 'b', 'c', 'b', 'd', 'a', 'e', 'f' ]; var b = [ 'b', 'd', 'a', 'e', 'f' ]; var c = _.union(a);
lodash uniq spread
var a = [ 'a', 'b', 'c', 'b', 'd', 'a', 'e', 'f' ]; var b = [ 'b', 'd', 'a', 'e', 'f' ]; var c = _.uniq(a);

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Suite status: <idle, ready to run>

Previous results

Test case name	Result
lodash union
lodash uniq spread

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Slowest: N/A

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

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Let's break down the provided JSON data and explain what is being tested.

**Benchmark Overview**

The benchmark measures the performance of three different approaches to merge two arrays in JavaScript: using `_.union` from Lodash, `object.assign()`, and creating a new array with unique elements using `_.uniq()` followed by spreading the original array (`_.spread()`).

**Options Compared**

1. **Lodash Union**: This method uses the `_` object's `union()` function to merge two arrays into a single array without duplicates.
2. **Object Assign**: This method uses the `object.assign()` method to create a new object with the merged arrays as properties.
3. **Unique Spread**: This method first uses Lodash's `_.uniq()` function to remove duplicates from one of the arrays, then spreads the original array using the spread operator (`...`) to merge it with the other array.

**Pros and Cons**

*   **Lodash Union**:
    *   Pros: Efficient way to merge two arrays without duplicates.
    *   Cons: Requires Lodash library to be included in the test environment.
*   **Object Assign**:
    *   Pros: Simple and straightforward approach, doesn't require any additional libraries.
    *   Cons: Creates a new object with merged properties, which may not be efficient for large arrays.
*   **Unique Spread**:
    *   Pros: Easy to implement and doesn't require Lodash library.
    *   Cons: May have performance issues if the original array is very large, as it needs to create an intermediate array with unique elements.

**Lodash Libraries**

1.  **_.union()**: This function merges two arrays into a single array without duplicates. It uses a Set data structure internally to efficiently remove duplicates.
2.  **_.uniq()**: This function removes duplicate elements from an array and returns a new array with unique elements. The spread operator (`...`) is used to merge the original array with the unique array.

**Special JavaScript Features/Syntax**

None mentioned in the provided benchmark JSON data.

**Other Alternatives**

If you're interested in exploring other approaches, here are some additional options:

1.  **Array.prototype.concat()**: This method merges two arrays into a single array.
2.  **Array.prototype.push() + Array.prototype.indexOf()**: You can use `push()` to add elements to the end of one array and then use `indexOf()` to check if an element exists in that array, effectively removing duplicates.
3.  **Set data structure**: If you're comfortable with working with Sets, you can convert both arrays into Set objects, merge them using `Set.prototype.union()`, and then convert the result back to an array.

Keep in mind that these alternatives might have different performance characteristics compared to the approaches mentioned in the benchmark.

Related benchmarks:

Array immutable union: lodash union vs object.assign vs unique (version: 0)

Comparing performance of: lodash union vs lodash uniq spread

Created: 5 years ago by: Guest

Jump to the latest result

lodash union

lodash uniq 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):