Benchmark: JavaScript spread operator vs Object.assign performance equivalent

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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**Benchmark Overview**

The provided benchmark, hosted on MeasureThat.net, compares the performance of two methods for merging objects in JavaScript: the spread operator (`...`) and `Object.assign()`. The test aims to determine which method is more efficient.

**Options Compared**

Two approaches are being compared:

1. **Spread Operator**: Using the spread operator (`...`) to merge objects.
2. **Object.assign()**: Using the `Object.assign()` method to merge objects.

**Pros and Cons of Each Approach**

* **Spread Operator (Using Spread)**:
	+ Pros:
		- Concise syntax, easy to read and write.
		- Can handle nested objects seamlessly.
	+ Cons:
		- May have a performance overhead due to the need for the interpreter or engine to parse and generate the code.
		- Limited support on older browsers (before ES6).
* **Object.assign()**:
	+ Pros:
		- Wide browser support, including older versions of Internet Explorer.
		- Can be used with `Array.prototype.push()` and other array methods for merging multiple objects.
	+ Cons:
		- More verbose syntax compared to the spread operator.
		- May require additional code to handle nested objects.

**Library Usage**

None of the test cases use any external libraries or frameworks. The tests are designed to demonstrate the performance difference between two built-in JavaScript features.

**Special JS Feature/Syntax**

The spread operator is a feature introduced in ES6 (EcmaScript 2015), which allows for concise object merging using the syntax `...`. This feature has been widely adopted by modern browsers and engines.

**Benchmark Preparation Code**

The provided benchmark preparation code is not necessary to understand the test itself, as it's embedded directly within the benchmark definition json. However, typically, such a script would prepare the objects and environments needed for the benchmark, ensuring consistency across different runs.

**Other Alternatives**

If the spread operator or `Object.assign()` were not options, other alternatives could include:

* **Destructuring**: Similar to the spread operator, but with an array-like syntax (e.g., `[a, b] = { a: 1, b: 2 }`).
* **Object.create()** and **Object.assign()**: Another way to merge objects using `Object.create()` and then `Object.assign()`.
* **Manual object merging**: A more verbose approach where each property is manually assigned from one object to another.

Keep in mind that these alternatives might have different performance characteristics, syntax complexities, or limitations compared to the spread operator and `Object.assign()`.

Related benchmarks:

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

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

Created: 3 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):