Benchmark: Custom Deep Merge vs Lodash Merge

HTML Preparation code:

<script src="https://raw.githubusercontent.com/lodash/lodash/4.17.15-npm/lodash.js"></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" }
			]
	}
]


// ------------------------------------------------------------------------
// ------------------------------------------------------------------------
// ------------------------------------------------------------------------

function isObject(item) {
  return item && typeof item === 'object' && !Array.isArray(item);
}

function merge(
  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]: {},
          });
        merge(target[key], source[key]);
      } else {
        Object.assign(target, {
          [key]: source[key],
        });
      }
    }
  }

  return merge(target, ...sources);
}

Tests:

custom deep merge
merge(obj1, obj2)
lodash
_.merge(obj1, obj2)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
custom deep merge
lodash

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.75 Safari/537.36

Browser/OS: Chrome 100 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
custom deep merge	2182049.8 Ops/sec
lodash	39959.5 Ops/sec

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

LLMs can make mistakes. Check important info.

The code snippet appears to be a benchmarking script written in JavaScript, specifically comparing the performance of a custom implementation of the `merge` function with the `_.merge` function from the Lodash library.

To answer your question, I'll provide an analysis of the code and offer some insights on how it could be improved or optimized.

**Code Analysis**

The code defines two functions: `isObject` and `merge`. The `isObject` function checks if a given item is an object using the `typeof` operator. The `merge` function takes two objects as input and merges them recursively, handling nested objects and arrays.

The benchmarking script uses Lodash's `_.merge` function for comparison with the custom implementation. It defines two test cases: one for the custom implementation (`custom deep merge`) and another for the Lodash library (`lodash`).

**Performance Comparison**

To compare the performance of the two implementations, we can analyze the latest benchmark result data.

From the provided data, Chrome 100 on a Mac OS X 10.15.7 desktop executes the custom `merge` function approximately 2182049.75 times per second, while Lodash's `_merge` function achieves around 39959.49 times per second.

**Insights and Suggestions**

1. **Optimization Opportunities**: The custom implementation could benefit from optimization techniques such as memoization or caching to reduce the overhead of recursive function calls.
2. **Error Handling**: Adding error handling mechanisms, like checking for null or undefined inputs, would make the code more robust and prevent potential errors.
3. **Code Refactoring**: The `merge` function's recursive structure could be made more explicit by using a loop or an iterative approach instead of recursion.
4. **Performance Comparison**: To gain a better understanding of the performance difference between the two implementations, consider adding more test cases with varying input sizes and data structures.

Overall, while the custom implementation demonstrates a good understanding of object merging, further optimization and refinement could improve its performance relative to Lodash's `_merge` function.

Related benchmarks:

Custom Deep Merge vs Lodash Merge (version: 0)

Comparing performance of: custom deep merge vs lodash

Created: 2 years ago by: Guest

Jump to the latest result

custom deep merge

lodash

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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