Benchmark: lodash merge vs object.assign vs spread

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);
object.assign
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = Object.assign(a, b);
spread
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = { ...a, ...b };

Historical Performance Data aggregated from 430 community runs

Desktop Results:

Chrome 348 runs

spread

32.8M/s

object.assign

12.8M/s

lodash merge

7.6M/s

Fastest: spread (4.3x faster)

View exact numbers

✓ spread: 32,830,470 ops/sec
• object.assign: 12,805,266 ops/sec
• lodash merge: 7,613,410 ops/sec

Firefox 48 runs

object.assign

26.5M/s

spread

12.5M/s

lodash merge

9.5M/s

Fastest: object.assign (2.8x faster)

View exact numbers

✓ object.assign: 26,475,322 ops/sec
• spread: 12,458,548 ops/sec
• lodash merge: 9,503,605 ops/sec

Other 9 runs

spread

25.1M/s

object.assign

7.7M/s

lodash merge

4.1M/s

Fastest: spread (6.2x faster)

View exact numbers

✓ spread: 25,114,498 ops/sec
• object.assign: 7,720,180 ops/sec
• lodash merge: 4,073,404 ops/sec

Safari 8 runs

spread

13.7M/s

object.assign

11.6M/s

lodash merge

5.5M/s

Fastest: spread (2.5x faster)

View exact numbers

✓ spread: 13,740,740 ops/sec
• object.assign: 11,569,088 ops/sec
• lodash merge: 5,533,571 ops/sec

Mobile Results:

Safari 11 runs

spread

13.7M/s

object.assign

11.6M/s

lodash merge

6.6M/s

Fastest: spread (2.1x faster)

View exact numbers

✓ spread: 13,688,065 ops/sec
• object.assign: 11,613,370 ops/sec
• lodash merge: 6,624,318 ops/sec

Chrome 6 runs

spread

12.0M/s

object.assign

4.3M/s

lodash merge

2.1M/s

Fastest: spread (5.6x faster)

View exact numbers

✓ spread: 11,996,528 ops/sec
• object.assign: 4,314,715 ops/sec
• lodash merge: 2,125,526 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
lodash merge
object.assign
spread

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/143.0.0.0 Safari/537.36

Browser/OS: Chrome 143 on Mac OS X 10.15.7

View result in a separate tab

object.assign

42.8M/s

spread

34.7M/s

lodash merge

15.8M/s

View exact numbers

Test name	Executions per second
✓ object.assign	42,837,576 Ops/sec
spread	34,650,320 Ops/sec
lodash merge	15,844,336 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to help explain the benchmark.

**What is being tested?**

MeasureThat.net is testing three different approaches for merging two objects in JavaScript:

1. `_.merge` from Lodash library
2. `Object.assign`
3. Spread syntax (`{ ...a, ...b }`)

These approaches are being compared to determine which one is the most efficient.

**Options comparison**

Here's a brief overview of each option and their pros and cons:

### 1. `_`

`.merge` from Lodash library

Pros:

* Well-maintained and widely used
* Supports complex merge logic (e.g., merging arrays, objects with nested properties)

Cons:

* Requires an external dependency (Lodash)
* May have slower startup times due to the dependency

The `_.merge` function takes two objects as input and returns a new merged object. It also supports other data types like arrays.

### 2. `Object.assign`

Pros:

* Built-in JavaScript method, no additional dependencies required
* Simple and straightforward implementation

Cons:

* Only works with objects, not with arrays or other data types
* Can lead to shallow merges if used incorrectly (i.e., merging an object into another object without creating a new target)

`Object.assign` is a built-in JavaScript function that takes multiple targets and an array of key-value pairs as arguments. When used with two objects, it returns a new merged object.

### 3. Spread syntax (`{ ...a, ...b }`)

Pros:

* Native JavaScript syntax, no additional dependencies required
* Works with both objects and arrays

Cons:

* Introduced in ECMAScript 2018 (ES2018), might not be supported by older browsers or environments
* Can lead to slower performance due to the creation of a new object

The spread syntax allows you to create a new object by spreading an existing object's properties onto a target object. When used with two objects, it returns a new merged object.

**Library and syntax features**

Lodash is a popular utility library for JavaScript that provides various functions for tasks like string manipulation, array processing, and more. In this benchmark, `_.merge` is used to merge objects.

The spread syntax (`{ ...a, ...b }`) is a modern JavaScript feature introduced in ECMAScript 2018 (ES2018). It allows you to create a new object by spreading an existing object's properties onto a target object.

**Other alternatives**

If these three approaches are not sufficient for your needs, here are some additional options:

* `Object.create`: can be used to create a new object with the desired properties, but it requires more code and might lead to shallow merges if used incorrectly.
* Custom merge functions: you can write your own custom function to merge objects, but this approach requires more code and expertise.

Keep in mind that the best approach depends on your specific use case, performance requirements, and the environment where your code will run.

lodash merge vs object.assign vs spread (version: 0)

Comparing performance of: `lodash merge vs object.assign vs spread`

Created: 8 years ago by: Registered User

Go to the latest result

lodash merge

object.assign

spread

Historical Performance Data aggregated from 430 community runs

Desktop Results:

Chrome 348 runs

Firefox 48 runs

Other 9 runs

Safari 8 runs

Mobile Results:

Safari 11 runs

Chrome 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

lodash merge vs object.assign vs spread (version: 0)

Comparing performance of: lodash merge vs object.assign vs spread

Created: 8 years ago by: Registered User

Go to the latest result

lodash merge

object.assign

spread

Historical Performance Data aggregated from 430 community runs

Desktop Results:

Chrome 348 runs

Firefox 48 runs

Other 9 runs

Safari 8 runs

Mobile Results:

Safari 11 runs

Chrome 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `lodash merge vs object.assign vs spread`