Benchmark: JavaScript spread operator vs Object.assign performance new objects

Tests:

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

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign

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 dive into the benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares the performance of two approaches to merge two JavaScript objects:

1. Using the spread operator (`...`)
2. Using `Object.assign()` with an empty object (`{}`) as the target object.

**What is being compared?**

The test cases create two sample objects: `firstObject` and `secondObject`, each containing some data. The benchmark then measures the time it takes to merge these two objects using:

1. The spread operator (`...`) syntax, which creates a new object with all properties from both `firstObject` and `secondObject`.
2. `Object.assign()`, which merges the properties of both objects into a single target object.

**Options Compared**

The benchmark is testing the performance difference between these two approaches:

Pros and Cons of each approach:

* **Spread Operator (`...`)**:
	+ Pros: concise, expressive syntax, creates a new object with all properties.
	+ Cons: can be slower due to creation of a new object, potentially slower than `Object.assign()` for large objects.
* **`Object.assign()`**:
	+ Pros: generally faster for large objects, as it modifies the target object in-place.
	+ Cons: less expressive syntax, can be confusing if not used correctly.

**Library Usage**

There is no specific library mentioned in the benchmark definition or test cases. However, `Object.assign()` is a built-in JavaScript method that is widely supported across browsers and platforms.

**Special JS Features/Syntax**

None are mentioned in this particular benchmark. The syntax used is standard JavaScript, with no special features or ES modules being utilized.

**Other Alternatives**

If you wanted to compare the performance of other object merging approaches, some alternatives could be:

* Using `Object.create()`, which creates a new object and sets its prototype to the specified object.
* Using `Object.defineProperties()` to merge properties from both objects into a single object.
* Using libraries like Lodash (`_merge()`) or Immutable.js (`merge()`), which provide more comprehensive merging functionality.

Keep in mind that these alternatives may have different performance characteristics compared to the spread operator and `Object.assign()`.

Related benchmarks:

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

Comparing performance of: Using the spread operator vs Using Object.assign

Created: 5 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

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):