Benchmark: JavaScript object spread operator vs Object.assign

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

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark JSON and explain what's being tested.

**Benchmark Definition**

The benchmark is defined in the `Benchmark Definition` section, which specifies two different approaches to merge two objects:

1. Using the spread operator (`...`)
2. Using `Object.assign`

The script preparation code is not provided, but it's likely that a function or method is being used to create the two objects to be merged.

**Options Compared**

Two options are compared in this benchmark:

1. **Using the spread operator (`...`)**: This approach uses the syntax `{ ...firstObject, ...secondObject }` to merge the two objects. The spread operator is a feature introduced in ECMAScript 2018 (ES2018) that allows you to expand an object into multiple expressions.
2. **Using `Object.assign()`**: This approach uses the `Object.assign()` method to merge the two objects. This method takes one or more source objects and merges them into a new target object.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

* **Using the spread operator (`...`)**:
	+ Pros:
		- More concise and expressive syntax
		- Can be used in destructuring declarations and other contexts where `Object.assign()` is not suitable
	+ Cons:
		- May have performance implications due to the creation of intermediate arrays (although this has improved with modern JavaScript engines)
* **Using `Object.assign()`**:
	+ Pros:
		- Well-established and widely supported syntax
		- Can be used in older browsers that don't support the spread operator
	+ Cons:
		- Less concise syntax
		- May require more code to achieve the same result

**Library**

There is no library mentioned in the benchmark definition.

**Special JS Feature or Syntax**

The use of the spread operator (`...`) is a special feature introduced in ECMAScript 2018 (ES2018). This allows you to expand an object into multiple expressions, making it a concise and expressive way to merge objects. If your target browser doesn't support ES2018, this approach may not be suitable.

**Other Alternatives**

If the spread operator is not supported or desired, other alternatives for merging objects include:

1. **Loose equal assignment (`=`)**: `const finalObject = firstObject; finalObject.sampleData = secondObject.sampleData; finalObject.moreData = secondObject.moreData;`
2. **Array methods (e.g., `concat()`, `spread()`)**
3. **Other libraries or functions for object merging**

Keep in mind that the choice of approach depends on the specific requirements and constraints of your project, including performance considerations, browser support, and code readability.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.80 Safari/537.36

Browser/OS: Chrome 75 on Windows

View result in a separate tab

Test name	Executions per second
Using the spread operator	4101446.8 Ops/sec
Using Object.assign	4516841.5 Ops/sec

Related benchmarks:

JavaScript object spread operator vs Object.assign (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 one month ago):