Benchmark: JavaScript spread operator vs Object.assign (to empty object) performance -1

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 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36

Browser/OS: Chrome 109 on Windows

View result in a separate tab

Test name	Executions per second
Using the spread operator	3435506.0 Ops/sec
Using Object.assign	7000765.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested on MeasureThat.net.

**Benchmark Overview**

The benchmark compares the performance of two approaches to merge two objects: using the spread operator (`...`) and using `Object.assign()`. The test creates two sample objects, `firstObject` and `secondObject`, with some data. Then, it constructs a final object by either spreading `firstObject` and `secondObject` using the spread operator or by using `Object.assign()` to merge them.

**Options Compared**

Two options are being compared:

1. **Using the spread operator (`...`)**: This approach uses the rest-spread syntax (`...firstObject, ...secondObject`) to merge the two objects.
2. **Using `Object.assign()`**: This approach uses the `Object.assign()` method with an empty object `{}` as the target to merge into.

**Pros and Cons of Each Approach**

* **Using the spread operator (`...`)**:
	+ Pros: More concise, easier to read, and arguably more expressive.
	+ Cons: May incur additional overhead due to the complexity of the syntax, and some browsers may not support it well.
* **Using `Object.assign()`**:
	+ Pros: Wide browser support, well-established syntax, and easy to understand.
	+ Cons: More verbose, requires explicit initialization of an empty object.

**Library Used**

The test uses `Object.assign()`, which is a built-in method in JavaScript's global scope. It's part of the ECMAScript standard since ECMAScript 2015 (ES6).

**Special JS Feature/Syntax**

None of the approaches use any special JavaScript features or syntax that would be unfamiliar to most software engineers.

**Other Alternatives**

If you need to merge objects, other alternatives include:

1. **Using a library like Lodash**: Lodash provides a `merge()` function that can handle more complex merging scenarios.
2. **Using the `{ ... }` syntax with a temporary object**: This approach uses an intermediate object (`{ firstObject: firstObject, secondObject: secondObject }`) to merge the two objects.

```javascript
const finalObject = {
  sampleData: firstObject.sampleData,
  moreData: secondObject.moreData,
};
```

However, this approach has a similar performance overhead to using `Object.assign()` and may not be as concise or expressive.

Related benchmarks:

JavaScript spread operator vs Object.assign (to empty object) performance -1 (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):