Benchmark: lodash.merge vs deepmerge vs custom

HTML Preparation code:

<script src="https://raw.githubusercontent.com/lodash/lodash/4.17.15-npm/lodash.js"></script>
<script src="https://unpkg.com/deepmerge/dist/umd.js"></script>
<script>
function isObject(item) {
    return (item && typeof item === 'object' && !Array.isArray(item));
}

function deepMerge(target, ...sources) {
    if (!sources.length) return target;
    const source = sources.shift();

    if (isObject(target) && isObject(source)) {
        for (const key in source) {
            if (isObject(source[key])) {
                if (!target[key]) Object.assign(target, { [key]: {} });
                deepMerge(target[key], source[key]);
            } else {
                Object.assign(target, { [key]: source[key] });
            }
        }
    }
    return deepMerge(target, ...sources);
}
</script>

Script Preparation code:

var obj1 = [
	{
		"id": "0001",
		"type": "donut",
		"name": "Cake",
		"ppu": 0.55,
		"batters":
			{
				"batter":
					[
						{ "id": "1001", "type": "Regular" },
						{ "id": "1002", "type": "Chocolate" },
						{ "id": "1003", "type": "Blueberry" },
						{ "id": "1004", "type": "Devil's Food" }
					]
			},
		"topping":
			[
				{ "id": "5001", "type": "None" },
				{ "id": "5002", "type": "Glazed" },
				{ "id": "5005", "type": "Sugar" },
				{ "id": "5007", "type": "Powdered Sugar" },
				{ "id": "5006", "type": "Chocolate with Sprinkles" },
				{ "id": "5003", "type": "Chocolate" },
				{ "id": "5004", "type": "Maple" }
			]
	},
	{
		"id": "0002",
		"type": "donut",
		"name": "Raised",
		"ppu": 0.55,
		"batters":
			{
				"batter":
					[
						{ "id": "1001", "type": "Regular" }
					]
			},
		"topping":
			[
				{ "id": "5001", "type": "None" },
				{ "id": "5002", "type": "Glazed" },
				{ "id": "5005", "type": "Sugar" },
				{ "id": "5003", "type": "Chocolate" },
				{ "id": "5004", "type": "Maple" }
			]
	},
	{
		"id": "0003",
		"type": "donut",
		"name": "Old Fashioned",
		"ppu": 0.55,
		"batters":
			{
				"batter":
					[
						{ "id": "1001", "type": "Regular" },
						{ "id": "1002", "type": "Chocolate" }
					]
			},
		"topping":
			[
				{ "id": "5001", "type": "None" },
				{ "id": "5002", "type": "Glazed" },
				{ "id": "5003", "type": "Chocolate" },
				{ "id": "5004", "type": "Maple" }
			]
	}
]

var obj2 = [
	{
		"id": "0001",
		"type": "donut",
		"name": "Cake",
		"ppu": 0.55,
		"batters":
			{
				"batter":
					[
						{ "id": "1001", "type": "Overwritten" },
						{ "id": "1002", "type": "Chocolate" },
						{ "id": "1003", "type": "Overwritten" },
						{ "id": "1004", "type": "Devil's Food" }
					]
			},
		"topping":
			[
				{ "id": "5001", "type": "Overwritten" },
				{ "id": "5002", "type": "Overwritten" },
				{ "id": "5005", "type": "Sugar" },
				{ "id": "5007", "type": "Powdered Sugar" },
				{ "id": "5006", "type": "Chocolate with Sprinkles" },
				{ "id": "5003", "type": "Chocolate" },
				{ "id": "5004", "type": "Overwritten" }
			]
	},
	{
		"id": "0002",
		"type": "Overwritten",
		"name": "Raised",
		"ppu": 0.55,
		"batters":
			{
				"batter":
					[
						{ "id": "1001", "type": "Overwritten" }
					]
			},
		"topping":
			[
				{ "id": "5001", "type": "None" },
				{ "id": "5002", "type": "Overwritten" },
				{ "id": "5005", "type": "Sugar" },
				{ "id": "5003", "type": "Chocolate" },
				{ "id": "5004", "type": "Maple" }
			]
	},
	{
		"id": "0003",
		"type": "Overwritten",
		"name": "Old Fashioned",
		"ppu": 0.55,
		"batters":
			{
				"batter":
					[
						{ "id": "1001", "type": "Overwritten" },
						{ "id": "1002", "type": "Chocolate" }
					]
			},
		"topping":
			[
				{ "id": "5001", "type": "None" },
				{ "id": "5002", "type": "Glazed" },
				{ "id": "5003", "type": "Chocolate" },
				{ "id": "5004", "type": "Maple" }
			]
	}
]

Tests:

Lodash.merge
_.merge(obj1, obj2)
deepmerge
deepmerge(obj1, obj2)
custom
deepMerge(obj1, obj2)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Lodash.merge
deepmerge
custom

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 28 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.6 Safari/605.1.15

Browser/OS: Safari 17 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Lodash.merge	92303.2 Ops/sec
deepmerge	103492.3 Ops/sec
custom	14484940.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 28 days ago):

LLMs can make mistakes. Check important info.

The provided JSON represents a benchmark comparison between three different approaches to merging objects in JavaScript using various libraries and a custom function. The specific options compared in this benchmark are:

1. **Lodash's merge function (`_.merge`)**:
   - **Library**: Lodash
     - **Purpose**: Lodash is a popular utility library in JavaScript that provides a range of functions for common programming tasks, including array manipulation, object manipulation, and more. Its `merge` function is specifically designed to deeply merge two or more objects, combining properties while recursively merging nested objects. If there are conflicting properties, `_.merge` will overwrite properties in the first object with properties from the later objects.
   - **Pros**: 
     - Well-tested and widely used.
     - Handles deep merging of objects out-of-the-box.
   - **Cons**: 
     - Can be relatively slow compared to custom implementations for certain use cases due to its comprehensive handling of various edge cases.
     - Adds a library dependency which may not be desired in all projects.

2. **Deepmerge library (`deepmerge`)**:
   - **Library**: deepmerge
     - **Purpose**: This library specifically handles deep merging of JavaScript objects. It allows users to customize the merge behavior, such as handling arrays or default values differently as per user-defined merge strategies.
   - **Pros**: 
     - Lightweight and focused solely on merging. 
     - Flexible, allowing customization of the merge process.
   - **Cons**: 
     - May not be as feature-rich as Lodash for other operations, which limits its general utility.

3. **Custom merge function (`deepMerge`)**:
   - **Implementation**: A custom implementation that recursively merges objects. It handles basic object merging by checking if both items are objects and merging them accordingly.
   - **Pros**: 
     - Can be tailored to specific application needs for performance or features.
     - No external dependencies, making it lightweight.
   - **Cons**: 
     - Likely less optimized than well-established libraries.
     - It may not cover all edge cases handled by dedicated libraries (like handling special cases for arrays or non-standard object types).

### Benchmark Results Overview
The benchmark results indicate the performance (in terms of executions per second) of each approach, which can give insight into their efficiency:

- **Custom Merge (`deepMerge`)**: 14,484,940 executions per second
- **deepmerge**: 103,492.32 executions per second
- **Lodash.merge**: 92,303.18 executions per second

The results show that the custom implementation significantly outperforms the two libraries, which might suggest it is more efficient for this specific use case. However, performance can vary based on the complexity and size of the objects being merged.

### Other Considerations
1. **Use Cases**: Choose `lodash.merge` if you want a reliable, general-purpose solution with extensive utility support. Choose `deepmerge` for specialized merge strategies or if you prefer a lightweight library for merging. Opt for the custom function if you need maximum performance in a constrained scenario and are confident in its robustness for your merging needs.

2. **Alternatives**: Other alternatives for object merging may include:
   - **Object.assign()**: A built-in method that can merge objects but only does a shallow copy.
   - **Spread syntax (`...`)**: Also does shallow merging and may involve a slight performance trade-off compared to deep merges.
   - **Immutable.js**: A library for handling data structures in an immutable way, which has its own merging capabilities but requires a different programming paradigm.

3. **Code Maintenance**: Consider the maintainability of the code. Using established libraries ensures that your merge functionality is robust against common pitfalls, whereas a custom implementation may require ongoing maintenance and testing.

In conclusion, the choice of method for merging objects should factor in performance, complexity, and project requirements, with careful consideration of the trade-offs of each approach.

Related benchmarks:

lodash.merge vs deepmerge vs custom (version: 1)

Comparing performance of: Lodash.merge vs deepmerge vs custom

Created: 28 days ago by: Guest

Jump to the latest result

Lodash.merge

deepmerge

custom

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 28 days ago):