Benchmark: my Spread vs assign

Tests:

assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign({}, firstObject, secondObject);
spread
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
assign
spread

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36

Browser/OS: Chrome 91 on Windows

View result in a separate tab

Test name	Executions per second
assign	2721873.5 Ops/sec
spread	1313919.8 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 in the provided benchmark.

The benchmark is comparing two approaches to merge objects: using `Object.assign()` and using the spread operator (`...`).

**Object.assign()**

This method takes two or more objects as arguments and returns a new object that contains all the properties from each of the argument objects. The properties are merged into the new object, but any existing properties in the new object will be overwritten.

Example:
```javascript
const firstObject = { sampleData: 'Hello world' };
const secondObject = { moreData: 'foo bar' };
const finalObject = Object.assign({}, firstObject, secondObject);
// finalObject now equals { sampleData: 'Hello world', moreData: 'foo bar' }
```
**Spread Operator (`...`)**

This syntax allows you to create a new object by spreading the properties of an existing object. When using the spread operator with two objects, it will merge their properties into a new object.

Example:
```javascript
const firstObject = { sampleData: 'Hello world' };
const secondObject = { moreData: 'foo bar' };
const finalObject = { ...firstObject, ...secondObject };
// finalObject now equals { sampleData: 'Hello world', moreData: 'foo bar' }
```
**Pros and Cons**

* `Object.assign()`: Pros - widely supported across browsers, easy to use. Cons - can be slower than the spread operator due to its method call overhead.
* Spread Operator (`...`): Pros - concise and efficient, no method call overhead. Cons - not all browsers support it.

**Library/Functions Used**

In this benchmark, the `Object.assign()` method is used as a built-in JavaScript function. The spread operator is also a part of the ECMAScript standard and is supported by most modern browsers.

**Special JS Feature/Syntax**

The benchmark uses a feature called "rest parameter syntax" (`...`) which was introduced in ECMAScript 2015 (ES6). This syntax allows you to pass an arbitrary number of arguments to a function, effectively creating an array of those arguments. In the context of object merging, it's used to spread the properties of one or more objects into another.

**Alternatives**

For merging objects, other alternatives include:

* Using `for...in` loop to iterate over each property and assign its value.
* Using a library like Lodash, which provides a `merge` function for this purpose.
* Using a different approach, such as using JSON merge strategies (e.g., [JSON Merge Strategies](https://www.npmjs.com/package/merge-strategies)).

However, the spread operator (`...`) is generally considered the most efficient and concise way to merge objects in modern JavaScript.

Related benchmarks:

my Spread vs assign (version: 0)

Comparing performance of: assign vs spread

Created: 3 years ago by: Guest

Jump to the latest result

assign

spread

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):