Benchmark: Array.prototype.concat vs spread operator

HTML Preparation code:

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

Tests:

lodash merge
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = _.merge(a, b);
spread operator
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = { a, ...b };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
lodash merge
spread operator

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the Benchmark Definition and individual test cases.

**Benchmark Definition**

The provided JSON represents a benchmark that compares two approaches to merge two objects in JavaScript: `_.merge` from Lodash library and the spread operator (`...`).

**Approaches compared**

1. **Lodash Merge**: The first approach uses the `_merge` function from Lodash, which is a utility library for functional programming tasks. This function recursively merges two objects into one.
2. **Spread Operator**: The second approach uses the spread operator (`...`) to merge two objects. When used in an assignment statement like `var c = { a, ...b };`, it creates a new object that includes all properties from both `a` and `b`.

**Pros and Cons**

*   Lodash Merge:
    *   Pros: More explicit and flexible way of merging objects, supports recursive merges.
    *   Cons: Requires importing an additional library (Lodash), may have performance overhead due to the recursive nature of its implementation.
*   Spread Operator:
    *   Pros: Simple and concise syntax, fast execution since it doesn't involve any library calls or recursion.
    *   Cons: May lead to less explicit code, and can be confusing if not used carefully.

**Library**

The Lodash library is a popular utility library for JavaScript that provides various functions for tasks like array manipulation, object merging, function chaining, etc. In this benchmark, `_merge` is specifically used for merging objects.

**Special JS feature or syntax**

None mentioned in the provided information.

**Other alternatives**

For merging objects without using the spread operator, other approaches could include:

*   Using the `Object.assign()` method: This method takes an object and assigns all properties from another object (or array of objects) to it.
*   Implementing a custom merge function that iterates over both objects and copies their properties.

Here's how you might implement these alternatives:

```javascript
// Object.assign() example
function mergeObjectsAssign(a, b) {
    return Object.assign({}, a, b);
}

// Custom implementation
function mergeObjectsCustom(a, b) {
    const result = {};
    for (const key in a) {
        if (b.hasOwnProperty(key)) {
            // Handle conflicts by using the spread operator or any other strategy.
            result[key] = [a[key], b[key]];
        } else {
            result[key] = a[key];
        }
    }
    for (const key in b) {
        if (!Object.prototype.hasOwnProperty.call(result, key)) {
            result[key] = b[key];
        }
    }
    return result;
}
```

Please note that these alternatives have their own trade-offs and might not be as efficient or concise as the spread operator.

**Benchmark Preparation Code**

The provided benchmark preparation code includes a script tag pointing to Lodash library:

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

This ensures that the `_merge` function from Lodash is available for use in the benchmark.

**Individual Test Cases**

The two test cases provided are designed to compare the performance of `_.merge()` and the spread operator (`...`) when merging objects.

Latest run results:

Run details: (Test run date: 6 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36

Browser/OS: Chrome 68 on Windows

View result in a separate tab

Test name	Executions per second
lodash merge	1673866.4 Ops/sec
spread operator	4008918.8 Ops/sec

Related benchmarks:

Array.prototype.concat vs spread operator (version: 0)

Compare the new ES6 spread operator with the traditional concat() method

Comparing performance of: lodash merge vs spread operator

Created: 6 years ago by: Guest

Jump to the latest result

lodash merge

spread operator

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):