Benchmark: JavaScript spread operator vs Object.assign performance123d

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const finalObject = { ...firstObject, data: 'foo bar', };
Using set
const firstObject = { sampleData: 'Hello world' } firstObject['data'] = 'foo bar'

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using set

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down what's being tested in this benchmark.

**Benchmark Goal**

The goal of this benchmark is to compare the performance of two approaches: using the JavaScript spread operator (`...`) and using the `set` method (specifically, assigning to an existing property).

**Options Compared**

Two options are being compared:

1. Using the JavaScript spread operator (`...`)
2. Using the `set` method (assigning to an existing property)

**Pros and Cons of Each Approach:**

### Using the Spread Operator (`...`)

* **Pros:**
	+ More concise and readable code
	+ Can be used to create new objects by copying existing ones, which can be more efficient than creating a new object from scratch
* **Cons:**
	+ May have performance overhead due to the creation of a new array or object property

### Using `set` Method

* **Pros:**
	+ Can be faster for simple assignment operations (assigning to an existing property)
	+ Does not create a new property or array element, which can reduce memory allocation and deallocation
* **Cons:**
	+ Less concise and readable code
	+ May require additional checks to ensure the property exists before assigning to it

**Library Used**

In this benchmark, no specific library is used beyond the JavaScript standard library.

**Special JS Feature or Syntax**

The `...` spread operator was introduced in ECMAScript 2015 (ES6) and allows for concise object creation. It's a relatively modern feature that has become widely supported across most browsers and engines.

**Other Considerations**

When deciding between these two approaches, consider the specific use case and performance requirements. If you need to create a new object by copying an existing one, using the spread operator might be more readable and efficient. However, if you're only assigning to an existing property, the `set` method might be faster due to its simplicity.

**Alternatives**

Other approaches for creating or modifying objects in JavaScript include:

* Using object literals (`{ ... }`)
* Using array destructuring (`[ ... ]`)
* Creating a new object by calling `Object.assign()` with an empty object as the first argument

Keep in mind that these alternatives may have different performance characteristics and readability trade-offs compared to using the spread operator or `set` method.

Related benchmarks:

JavaScript spread operator vs Object.assign performance123d (version: 0)

Comparing performance of: Using the spread operator vs Using set

Created: 4 years ago by: Registered User

Jump to the latest result

Using the spread operator

Using set

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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