Benchmark: Merging array of objects [Lodash merge vs Array.prototype.reduce merge] v2

HTML Preparation code:

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

Script Preparation code:

var x = null;
var testObjectArray = [{
    a: 1
}, {
    b: 1
}, {
    c: [1, 2, 3]
}, {
    d: "hello"
}, {
    e: "e",
    f: "f"
}];

var reduceMergeArrow = (objectArray) => objectArray.reduce(((accumulator, object) => Object.assign(accumulator, object)))
function reduceMerge(objectArray) {
  return objectArray.reduce(((accumulator, object) => Object.assign(accumulator, object)));
}

Tests:

lodash merge spread
x = _.merge(...testObjectArray);
lodash merge loop
x = {} for(const object in testObjectArray) { x = _.merge(x, object); }
reduce merge arrow
x = reduceMergeArrow(testObjectArray);
reduce merge
x = reduceMerge(testObjectArray);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
lodash merge spread
lodash merge loop
reduce merge arrow
reduce merge

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 break down the provided benchmark and explain what's being tested, compared, and their pros and cons.

**Benchmark Overview**

The benchmark measures the performance of three approaches to merging an array of objects:

1. `reduceMergeArrow` (using arrow function)
2. `reduceMerge` (without using arrow function)
3. Lodash's `merge` function with spread syntax (`_.merge(...testObjectArray)`)

**Approach 1: reduceMergeArrow**

The `reduceMergeArrow` approach uses the `reduce` method on an array of objects, and passes an arrow function that merges two objects together.

```javascript
var reduceMergeArrow = (objectArray) => objectArray.reduce(((accumulator, object) => Object.assign(accumulator, object)))
```

Pros:

* Simple and concise code
* Easy to read and understand

Cons:

* Might be less efficient due to the overhead of creating a new accumulator object on each iteration
* Uses arrow function, which can be slower than traditional function calls in some cases

**Approach 2: reduceMerge**

The `reduceMerge` approach uses the same `reduce` method as before, but without using an arrow function.

```javascript
function reduceMerge(objectArray) {
  return objectArray.reduce(((accumulator, object) => Object.assign(accumulator, object)));
}
```

Pros:

* Might be faster than `reduceMergeArrow` due to fewer overheads
* Still easy to read and understand

Cons:

* Requires defining a separate function for the reduction logic
* Less concise than `reduceMergeArrow`

**Approach 3: Lodash's merge with spread syntax**

The third approach uses Lodash's `merge` function with spread syntax (`_.merge(...testObjectArray)`).

```javascript
x = _.merge(...testObjectArray);
```

Pros:

* Fast and efficient, as Lodash's implementation is optimized for performance
* Convenient and concise way to merge objects

Cons:

* Requires including an external library (Lodash)
* Might be slower than the other approaches due to the overhead of importing a third-party library

**Library: Lodash**

Lodash is a popular JavaScript utility library that provides various functions for tasks like string manipulation, array manipulation, and object merging. In this benchmark, we're using Lodash's `merge` function to merge an array of objects.

Pros:

* Fast and efficient
* Convenient and concise way to perform common operations

Cons:

* Requires including an external library
* Might not be suitable for all projects due to its size and dependencies

**Special JS feature: Arrow functions**

Arrow functions are a feature introduced in ECMAScript 2015 that allow for more concise and expressive code. In the `reduceMergeArrow` approach, we're using an arrow function as the reduction logic.

Pros:

* More concise and readable code
* Easier to understand and maintain

Cons:

* Might be slower than traditional function calls due to the overhead of creating a new scope object

**Benchmark Results**

The benchmark results show that the performance order from fastest to slowest is:

1. `reduceMerge` (without arrow function) - 144,674.5 executions per second
2. Lodash's `merge` with spread syntax (`_.merge(...testObjectArray)`) - 189,624.90625 executions per second
3. `reduceMergeArrow` (with arrow function) - 243,610.3 executions per second

These results indicate that the `reduceMerge` approach is the fastest, followed closely by Lodash's `merge` with spread syntax.

**Other Alternatives**

If you don't want to use a third-party library like Lodash, you could consider implementing your own merge function using a loop or recursion. However, these approaches might be slower and less concise than the ones presented in the benchmark.

Another alternative is to use a JavaScript implementation of a merge algorithm from an existing programming language, such as Java's `Merge` class. However, this approach would require significant modifications to the original codebase and might not be feasible for most projects.

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36

Browser/OS: Chrome 126 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
lodash merge spread	1446674.5 Ops/sec
lodash merge loop	189624.9 Ops/sec
reduce merge arrow	2436103.0 Ops/sec
reduce merge	2473860.8 Ops/sec

Related benchmarks:

Merging array of objects [Lodash merge vs Array.prototype.reduce merge] v2 (version: 0)

Comparing performance of: lodash merge spread vs lodash merge loop vs reduce merge arrow vs reduce merge

Created: 4 years ago by: Guest

Jump to the latest result

lodash merge spread

lodash merge loop

reduce merge arrow

reduce merge

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):