Benchmark: JavaScript spread operator vs Object.assign performance no mut

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign({}, firstObject, secondObject);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36

Browser/OS: Chrome 114 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Using the spread operator	2570740.2 Ops/sec
Using Object.assign	6148630.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided benchmark, hosted on MeasureThat.net, compares the performance of two approaches for merging objects in JavaScript: using the spread operator (`...`) and `Object.assign()`. The test creates two sample objects, merges them into a third object, and measures the execution time.

**Options Compared**

1. **Spread Operator (Rest Spreading)**: This approach uses the syntax `{ ...firstObject, ...secondObject }` to merge two objects.
2. **Object.assign()**: This approach uses the `Object.assign()` method to merge two objects, passing an empty object as the target object.

**Pros and Cons of Each Approach**

1. **Spread Operator (Rest Spreading)**:
	* Pros:
		+ More concise and readable syntax
		+ Less memory allocation required (since it doesn't create a new object)
	* Cons:
		+ May not be supported in older browsers or JavaScript engines
2. **Object.assign()**:
	* Pros:
		+ Widely supported across browsers and JavaScript engines
		+ Provides more control over the merging process (e.g., setting default values)
	* Cons:
		+ Less concise syntax, making it less readable
		+ Requires creating an empty object as the target, which can lead to additional memory allocation

**Library Used**

None, only built-in JavaScript methods are used.

**Special JS Feature or Syntax**

The spread operator (`...`) is a relatively recent feature introduced in ECMAScript 2018 (ES2018). It's a part of the rest parameter syntax and allows for concise object merging. The `Object.assign()` method has been around since ECMAScript 5 (ES5) and provides more flexibility in merging objects.

**Other Considerations**

When choosing between these approaches, consider the trade-offs between conciseness, readability, and performance. For simple merges, the spread operator might be a better choice due to its concise syntax. However, if you need more control over the merging process or support older browsers, `Object.assign()` is a safer bet.

**Alternative Approaches**

Other approaches for merging objects in JavaScript include:

* Using the `concat()` method: `const finalObject = Object.assign({}, firstObject).concat(secondObject)`
* Using the `merge()` method from libraries like Lodash: `_ merge(firstObject, secondObject)`
* Using destructuring assignment: `const { ...firstObject, ...secondObject } = firstObject; const finalObject = { ...finalObject, ...secondObject };` (note that this approach requires modern JavaScript support)

Keep in mind that these alternatives might have different performance characteristics and compatibility issues depending on the browser or JavaScript engine used.

Related benchmarks:

JavaScript spread operator vs Object.assign performance no mut (version: 0)

Comparing performance of: Using the spread operator vs Using Object.assign

Created: one year ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

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):