Benchmark: assign vs spread

Tests:

a1
x = {a: 10, b: 20, c: 30} x = Object.assign({}, x, {d: 100})
b1
x = {a: 10, b: 20, c: 30} x = {...x, d: 100}

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
a1
b1

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

I'll break down the provided JSON and explain what's being tested, compared, and the pros/cons of each approach.

**Benchmark Definition**
The benchmark is designed to compare two approaches for assigning new properties to an object in JavaScript:

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

**Script Preparation Code**
There is no script preparation code provided, which means that the script starts with a clean slate and the tests are executed from scratch each time.

**Html Preparation Code**
Again, there is no html preparation code provided, indicating that the benchmark focuses solely on JavaScript performance and does not consider HTML-related factors.

**Individual Test Cases**

1. **Test Case "a1"**
The benchmark definition uses `Object.assign()`: `x = {a: 10, b: 20, c: 30}\r\nx = Object.assign({}, x, {d: 100})`
	* The test creates an object `x` with properties `a`, `b`, and `c`.
	* It then uses `Object.assign()` to create a new object by copying the original `x` object's properties (`{a: 10, b: 20, c: 30}`) and adding a new property `d` with value `100`.
2. **Test Case "b1"**
The benchmark definition uses the spread operator (`...`): `x = {a: 10, b: 20, c: 30}\r\nx = {...x, d: 100}`
	* The test creates an object `x` with properties `a`, `b`, and `c`.
	* It then uses the spread operator to create a new object by copying the original `x` object's properties (`{a: 10, b: 20, c: 30}`) and adding a new property `d` with value `100`.

**Library Usage**
Neither test case uses any external libraries. The focus is on comparing the performance of these two JavaScript constructs.

**Special JS Features/Syntax**
The benchmark utilizes the spread operator (`...`) introduced in ECMAScript 2015 (ES6). This syntax allows for creating new objects by copying an existing object's properties and adding or overriding new ones.

**Other Alternatives**

If you were to use alternative approaches, here are a few options:

1. Using `forEach()` with `Object.defineProperty()`: `x = {a: 10, b: 20, c: 30}; Object.keys(x).forEach((key) => { Object.defineProperty(x, key, { value: x[key] + 100 }); })`
2. Using a loop with property assignment: `for (var i in x) { x[i] = x[i] + 100; }`
3. Using `Object.assign()` in a different way (e.g., by using an array of properties or objects to assign): `x = Object.assign({}, x, [{ d: 100 }])`

Keep in mind that these alternatives may not be as efficient or readable as the original spread operator or `Object.assign()` examples.

Latest run results:

Run details: (Test run date: 2025 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36

Browser/OS: Chrome 63 on Mac OS X 10.12.4

View result in a separate tab

Test name	Executions per second
a1	575428.2 Ops/sec
b1	716861.1 Ops/sec

Related benchmarks:

assign vs spread (version: 0)

Comparing performance of: a1 vs b1

Created: 6 years ago by: Guest

Jump to the latest result

a1

b1

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):