Benchmark: JS Spread vs Object.assign

Tests:

Using spread
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 spread
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 break down what's being tested in this benchmark.

**What is being tested?**

The benchmark compares the performance of two methods to merge objects: the spread operator (`...`) and `Object.assign()`.

**Options compared:**

* **Spread Operator (REST/ES6)**: A shorthand syntax introduced in ECMAScript 2015 that allows you to expand an object into a new object, merging properties from both sources.
* **`Object.assign()` method**: A built-in JavaScript method that copies the values of all enumerable own properties from one or more source objects to a target object.

**Pros and Cons:**

* **Spread Operator (REST/ES6)**:
	+ Pros:
		- More concise and readable code
		- Works with modern browsers and Node.js environments
		- Less prone to errors due to its syntax
	+ Cons:
		- May be slower than `Object.assign()` in older JavaScript engines or environments that don't support the spread operator.
* **`Object.assign()` method**:
	+ Pros:
		- Faster execution time, especially in older JavaScript engines or environments with limited support for modern methods.
		- Works across a broader range of browsers and Node.js versions.
	+ Cons:
		- Less readable code due to the function call syntax.
		- More prone to errors if not used correctly.

**Library/Language features:**

* The benchmark doesn't explicitly mention any specific library, but it does use modern JavaScript features like the spread operator. If you're targeting older browsers or environments that don't support these features, you may need to add polyfills or fallbacks.
* There are no special JS features or syntax being tested; both options rely on standard JavaScript semantics.

**Other considerations:**

* **Benchmarking nuances:** When benchmarking performance-critical code, it's essential to consider factors like cache effects, variable scope, and execution context. The spread operator might exhibit different behavior depending on the specific use case and environment.
* **Platform differences:** The benchmark is run on a Mac OS X 10.15.7 system, which may have different optimization patterns or performance characteristics compared to other platforms.

**Alternatives:**

If you need an alternative to these two methods, consider using:

* **Lodash's `merge()` method**: A utility function that merges objects in a way similar to the spread operator.
* **Underscore.js's `_extend()` function**: Another utility function that merges objects in a way similar to `Object.assign()`.
* **Other merging libraries or functions**: Depending on your specific requirements, you might find other suitable alternatives, such as using a library like Immutable.js for immutable data structures.

Related benchmarks:

JS Spread vs Object.assign (version: 0)

Spread operator vs Object.assign

Comparing performance of: Using spread vs Using Object.assign

Created: 3 years ago by: Guest

Jump to the latest result

Using spread

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):