Benchmark: JavaScript spread operator vs Object.assign performance 4

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.

**What is being tested?**

MeasureThat.net is testing the performance difference between two ways of merging objects in JavaScript: using the spread operator (`...`) and `Object.assign()`. The test creates two sample objects, `firstObject` and `secondObject`, with some data. Then it tries to merge these objects into a new object, `finalObject`, using both methods.

**Options being compared**

There are two options being compared:

1. **Using the spread operator (`...`)**: This method uses the rest/spread syntax to create a new object that includes all properties from `firstObject` and `secondObject`.
2. **Using `Object.assign()`**: This method creates a new object by cloning an existing object (`{}`) and then merges properties from `firstObject` and `secondObject` using the spread operator.

**Pros and cons of each approach**

1. **Using the spread operator (`...`)**:
	* Pros: More concise and readable, especially when merging multiple objects.
	* Cons: May be slower than `Object.assign()` because it involves creating a new object and then spreading properties into it.
2. **Using `Object.assign()`**:
	* Pros: Faster than the spread operator, as it only creates a shallow clone of the original object and then merges properties.
	* Cons: Less concise and less readable, especially when merging multiple objects.

**Other considerations**

Both methods have their trade-offs in terms of performance and readability. The spread operator is more modern and readable, but may be slower. `Object.assign()` is older and more widely supported, but may be less readable.

It's worth noting that the benchmark measures the number of executions per second, which suggests that performance is a key consideration here.

**Library**

Neither of these methods uses any external libraries. They are built-in JavaScript features.

**Special JS feature or syntax**

The spread operator (`...`) is a relatively recent addition to JavaScript (introduced in ECMAScript 2015) and is used to create new objects by spreading properties from an existing object.

**Benchmark results**

According to the latest benchmark result, Firefox 70 on a Mac OS X 10.14 desktop executes `Object.assign()` approximately 27% faster than using the spread operator.

**Other alternatives**

If you're interested in exploring alternative methods for merging objects, some other options include:

* Using `Object.create()`: This method creates a new object by cloning an existing object and then merging properties.
* Using a library like Lodash's `merge()` function: This function provides a more concise way to merge objects, but may introduce additional overhead.

However, it's worth noting that the benchmark is primarily focused on comparing the performance of these two built-in methods.

Related benchmarks:

JavaScript spread operator vs Object.assign performance 4 (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):