Benchmark: Spread Operator VS Object.assign performance analysis

Tests:

Spread Operator
const state = { a: 1, b: 2 }; return { ...state, a: 2, b: 1 };
Object.assign
const state = { a: 1, b: 2 }; return Object.assign({}, { ...state, a:2, b: 1 });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Spread Operator
Object.assign

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and discussed.

**What is being tested?**

The benchmark compares two approaches to create a new object by spreading an existing object and modifying its properties: the spread operator (`...`) and `Object.assign()`. The test case uses an example JavaScript object `state` with two properties: `a` and `b`, both initialized with different values.

**Options compared**

Two options are being compared:

1. **Spread Operator (`...`)**: This approach uses the spread operator to create a new object by copying all properties from `state` and adding new ones (`a: 2, b: 1`). The syntax is `const newState = { ...state, a: 2, b: 1 };`.
2. **Object.assign()**: This approach uses the `Object.assign()` method to create a new object by copying all properties from an existing object (in this case, `state`) and adding new ones (`a:2, b: 1`). The syntax is `const newState = Object.assign({}, { ...state, a:2, b: 1 });`.

**Pros and Cons of each approach**

**Spread Operator**

Pros:

* More concise and expressive syntax
* Can be used with destructuring and other JavaScript features

Cons:

* May have performance overhead due to the need for string interpolation or concatenation
* Not supported in older browsers or environments

**Object.assign()**

Pros:

* Widely supported across most modern browsers and environments
* Does not require explicit string interpolation or concatenation

Cons:

* Less concise syntax compared to the spread operator
* May have performance overhead due to the need for object creation and property addition

**Other considerations**

When using the spread operator, it's essential to note that if you're using a recent version of JavaScript (ECMAScript 2018), you can use rest syntax (`{ ...state }`) which is more concise.

In terms of performance, both approaches are similar in terms of their complexity. However, some benchmarks suggest that the spread operator might be slightly slower due to the need for string interpolation or concatenation.

**Library and syntax**

There's no specific library being used in this benchmark, but `Object.assign()` relies on the ECMAScript 3 standard method for creating objects by copying properties from an existing object.

No special JavaScript features are being tested or discussed in this benchmark.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36

Browser/OS: Chrome 105 on Windows

View result in a separate tab

Test name	Executions per second
Spread Operator	59912924.0 Ops/sec
Object.assign	4053259.5 Ops/sec

Related benchmarks:

Spread Operator VS Object.assign performance analysis (version: 0)

Comparing performance of: Spread Operator vs Object.assign

Created: 2 years ago by: Guest

Jump to the latest result

Spread Operator

Object.assign

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):