Benchmark: JavaScript assignment vs Object.assign performance

Tests:

Using the spread operator
const firstObject = { sampleData: ()=>{return 1+1;} } const secondObject = { moreData: 'foo bar' } let finalObject = {}; finalObject['firstObject'] = firstObject.sampleData; finalObject['secondObject'] = secondObject.moreData;
Using Object.assign
const firstObject = { sampleData: ()=>{return 1+1;} } 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: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.5005.167 YaBrowser/22.7.5.1018 Yowser/2.5 Safari/537.36

Browser/OS: Yandex Browser 22 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Using the spread operator	797719808.0 Ops/sec
Using Object.assign	4411901.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases.

**Benchmark Definition:**

The benchmark is comparing two approaches for assigning data to an object in JavaScript:

1. **Using the spread operator**: This approach uses the spread operator (`...`) to create a new object by spreading the properties of `firstObject` and `secondObject`.
2. **Using Object.assign**: This approach uses the `Object.assign()` method to assign the properties of `firstObject` and `secondObject` to a new object, `finalObject`.

**Pros and Cons:**

* **Using the spread operator:**
	+ Pros:
		- Concise and readable syntax.
		- Can create a new object with the desired properties.
	+ Cons:
		- May be slower than `Object.assign()` due to the creation of a new object.
		- Can lead to unnecessary memory allocations if not used carefully.
* **Using Object.assign:**
	+ Pros:
		- Efficient and optimized by modern JavaScript engines.
		- Allows for more control over the assignment process.
	+ Cons:
		- Less readable syntax compared to the spread operator.
		- May require additional logic to handle complex assignments.

**Library and Syntax Features:**

* **No external libraries are used** in this benchmark. The test cases only utilize built-in JavaScript features.
* No special JavaScript features or syntax are mentioned in the provided benchmark definition.

**Other Considerations:**

When writing performance-critical code, it's essential to consider the following factors:

* **Memory allocation**: Creating a new object can lead to memory allocations, which can impact performance.
* **Cache locality**: Assigning properties to an object can affect cache locality, which can influence execution speed.
* **Browser optimizations**: Modern JavaScript engines have various optimizations and caching mechanisms that can impact benchmark results.

**Alternatives:**

If you're interested in exploring alternative approaches or libraries for assigning data to objects, consider the following options:

1. **Array.prototype.assign() method**: Introduced in ECMAScript 2015, this method provides a similar interface to `Object.assign()` but with additional features.
2. **lodash.assign() function**: A popular utility library (Lodash) that provides an implementation of the `assign` method with various options and shortcuts.
3. **Other object assignment libraries or polyfills**: Depending on your specific requirements, you might find alternative libraries or polyfills that provide more advanced features or compatibility.

Keep in mind that these alternatives may introduce additional dependencies, complexity, or performance overhead, so it's essential to evaluate their trade-offs carefully.

Related benchmarks:

JavaScript assignment vs Object.assign performance (version: 0)

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

Created: 5 years 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):