Benchmark: JavaScript spread operator vs Object.assign performance 3

Tests:

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

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.102 Safari/537.36

Browser/OS: Chrome 85 on Windows

View result in a separate tab

Test name	Executions per second
Using Object.assign	2272776.2 Ops/sec
Using spread op	2722642.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**What is tested?**

The provided benchmark tests two approaches to merge two objects in JavaScript: using `Object.assign()` and using the spread operator (`...`).

**Options compared**

Two options are compared:

1. **Using `Object.assign()`**: This method takes multiple arguments, including the source object(s) to be merged.
2. **Using the spread operator (`...`)**: This method takes an object literal with multiple properties, which can be merged into a new object.

**Pros and Cons**

Here are some pros and cons of each approach:

**Using `Object.assign()`**:

Pros:

* Well-established and widely supported
* Can handle merging objects with different data types (e.g., strings, numbers, booleans)
* Can be used to merge multiple source objects into a single object

Cons:

* Requires creating a new object or modifying an existing one
* Can lead to shallow copying issues if not used carefully
* May have performance implications due to function call overhead

**Using the spread operator (`...`)**:

Pros:

* More concise and readable than `Object.assign()`
* Supports merging objects with different data types (e.g., strings, numbers, booleans)
* Can be used to merge multiple source objects into a single object

Cons:

* Less well-established than `Object.assign()` (introduced in ECMAScript 2018)
* May have performance implications due to function call overhead
* Not supported in older browsers or environments that don't support ES6+ syntax

**Library usage**

Neither of the two options relies on any external libraries. Both approaches use native JavaScript features.

**Special JS feature/syntax**

The test case uses the spread operator (`...`), which is a new syntax introduced in ECMAScript 2018. This allows for more concise object merging and is widely supported in modern browsers and environments.

**Benchmark preparation code**

The benchmark preparation code is not provided, but based on the `Benchmark Definition`, it appears to create two objects: `firstObject` and `secondObject`. The `finalObject` is created by either using `Object.assign()` or the spread operator, depending on the test case.

**Other alternatives**

If you were to implement an alternative approach for merging objects, some options could include:

* Using the `merge` function from a library like Lodash
* Implementing a custom merge function that iterates over object properties and merges them recursively
* Using a binary search approach to find common keys between source objects

Keep in mind that these alternatives might have different performance characteristics and may not be as concise or readable as using `Object.assign()` or the spread operator.

Related benchmarks:

JavaScript spread operator vs Object.assign performance 3 (version: 0)

Comparing performance of: Using Object.assign vs Using spread op

Created: 4 years ago by: Guest

Jump to the latest result

Using Object.assign

Using spread op

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):