Benchmark: JavaScript spread operator vs Object.assign (with new 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

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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 and compare the different approaches.

**Benchmark Definition**

The benchmark is designed to measure the performance difference between two ways of merging objects in JavaScript: using the spread operator (`...`) and `Object.assign()` with a new object.

**Options Compared**

There are two options compared:

1. **Using the Spread Operator**: This approach uses the `...` operator to merge two objects into a new one.
```javascript
const finalObject = { ...firstObject, ...secondObject };
```
2. **Using Object.assign() with a New Object**: This approach uses the `Object.assign()` method to merge two objects into a new one, but creates a new object as an intermediate step.
```javascript
const finalObject = Object.assign({}, firstObject, secondObject);
```
**Pros and Cons**

* **Using the Spread Operator**:
	+ Pros: concise and expressive syntax, efficient performance (as it avoids creating a new object).
	+ Cons: may not be immediately clear to developers without experience with this feature.
* **Using Object.assign() with a New Object**:
	+ Pros: more explicit and maintainable code, easier to understand for developers without experience with the spread operator.
	+ Cons: creates an intermediate object, which can lead to increased memory usage.

**Library**

There is no specific library being tested in this benchmark. However, `Object.assign()` is a built-in method of the JavaScript `Object` prototype.

**Special JS Feature/Syntax**

The use of the spread operator (`...`) is a special feature introduced in ECMAScript 2018 (ES2018). It allows objects to be expanded into new objects.

**Other Alternatives**

There are other ways to merge objects in JavaScript, such as using the `merge()` method from the `lodash` library or creating an object using the `{ ... }` syntax and then updating its properties. However, these alternatives are not being tested in this benchmark.

In summary, the benchmark is testing two approaches for merging objects in JavaScript: using the spread operator (`...`) and `Object.assign()` with a new object. The results show that both approaches have similar performance characteristics, but the spread operator is more concise and efficient.

Related benchmarks:

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

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

Created: 2 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):