Benchmark: JavaScript spread operator vs Object.assign of empty object performance

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 JSON represents a JavaScript microbenchmark on MeasurThat.net, which compares the performance of using the spread operator (`...`) to merge objects versus using the `Object.assign()` method.

**Test Cases**

There are two test cases:

1. **Using the Spread Operator**: This test case uses the spread operator to merge two objects: `firstObject` and `secondObject`. The resulting object is assigned to a new variable, `finalObject`.
2. **Using Object.assign**: This test case uses the `Object.assign()` method to merge the same two objects (`firstObject` and `secondObject`) into a new object, also named `finalObject`.

**Options Compared**

The benchmark compares the performance of these two approaches:

1. **Spread Operator (`...`)**: This approach is often considered more concise and readable. It creates a shallow copy of the first object and then spreads its properties onto the second object.
2. **`Object.assign()`**: This approach is more explicit and widely supported, as it can be used to merge objects in other contexts beyond just literal objects.

**Pros and Cons**

* **Spread Operator (`...`)**:
	+ Pros:
		- Concise and readable
		- Creates a shallow copy of the first object, which might be desirable in some cases
	+ Cons:
		- Can lead to unexpected behavior if used with non-object values (e.g., numbers or booleans)
		- Might be slower due to the overhead of creating a new object and spreading its properties
* **`Object.assign()`**:
	+ Pros:
		- More explicit and easier to understand for developers familiar with other languages that use `assign()`
		- Can handle non-object values without issues
	+ Cons:
		- Less concise and less readable compared to the spread operator
		- Might lead to slower performance due to the overhead of creating a new object

**Library/Functionality Used**

In both test cases, the `Object` function is used. The `Object.assign()` method is a part of the ECMAScript standard and is widely supported by most modern browsers.

**Special JS Features/Syntax**

There are no special JavaScript features or syntax mentioned in this benchmark.

**Other Alternatives**

If you're interested in exploring alternative approaches, here are a few options:

1. **Destructuring Assignment**: Similar to the spread operator, destructuring assignment can be used to merge objects. However, it's more commonly used for destructuring arrays and objects in other contexts.
2. **`Object.create()`**: This method creates a new object with the specified prototype. It can be used as an alternative to `Object.assign()`, but its usage is less common.

Keep in mind that these alternatives might not provide significant performance differences or offer better readability compared to the spread operator and `Object.assign()`.

Related benchmarks:

JavaScript spread operator vs Object.assign of empty object performance (version: 0)

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

Created: 6 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):