Benchmark: spread undefined vs empty object

Tests:

undefined
for (let i = 0, n = 10000; i < n; i++) { const obj = { ...undefined }; }
empty
for (let i = 0, n = 10000; i < n; i++) { const obj = { ...{} }; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
empty

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/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
undefined	1703.3 Ops/sec
empty	9472.9 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark definition and test cases to understand what is being tested.

**What is being tested?**

The provided benchmark tests two different approaches to creating objects in JavaScript:

1. Using the spread operator (`...`) with `undefined` as an argument.
2. Using the spread operator (`...`) with an empty object (`{}`) as an argument.

In other words, the benchmark is comparing the performance of these two approaches.

**Options compared**

The two options being compared are:

* Option 1: `const obj = { ...undefined }`
* Option 2: `const obj = { ...{} }`

Both options use the spread operator to create a new object. The difference lies in what is spread from `undefined` or `{}`.

**Pros and Cons of each approach**

1. **Option 1: `const obj = { ...undefined }`**
	* Pros:
		+ Simpler syntax, as it only requires spreading an empty object.
	* Cons:
		+ Performance may be slower due to the overhead of using `undefined`.
2. **Option 2: `const obj = { ...{} }`**
	* Pros:
		+ Performance may be faster due to the use of a valid object reference.
	* Cons:
		+ More complex syntax, as it requires spreading an empty object.

**Other considerations**

When using the spread operator with `undefined`, JavaScript creates a new object that inherits properties from `undefined`. This can lead to unexpected behavior and performance issues.

In contrast, when using the spread operator with an empty object, JavaScript creates a shallow copy of the object, which is a more efficient approach.

**Library or special JS feature**

There are no libraries or special JS features being tested in this benchmark. The focus is solely on comparing the two approaches to creating objects using the spread operator.

**Special JS syntax**

The benchmark uses ES6 syntax for spreading objects and `const` declarations, which is a common syntax in modern JavaScript codebases.

**Other alternatives**

If you're interested in exploring alternative ways to create objects, here are a few options:

* Using the `Object.assign()` method: `const obj = Object.assign({}, undefined);`
* Using the `JSON.parse()` method: `const obj = JSON.parse(JSON.stringify(undefined));` (Note: This creates a new object that inherits properties from `undefined`, similar to Option 1)
* Using a library like Lodash or Immutable.js for object creation and manipulation

Keep in mind that these alternatives may have different performance characteristics, syntax, and use cases compared to the original benchmark.

Related benchmarks:

spread undefined vs empty object (version: 0)

Comparing performance of: undefined vs empty

Created: 2 years ago by: Guest

Jump to the latest result

undefined

empty

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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