Benchmark: JavaScript spread operator vs Object.assign performance (2)

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 world of JavaScript microbenchmarks!

**Benchmark Definition**

The provided JSON represents a benchmark that tests the performance of two approaches: using the spread operator (`...`) and `Object.assign()` to create a new object by merging two existing objects.

**Approaches Compared**

1. **Using the Spread Operator (```javascript
const finalObject = { ...firstObject, ...secondObject };
```
)**

The spread operator is a feature introduced in ECMAScript 2018 (ES2018) that allows you to expand an object into multiple arguments or properties. In this benchmark, it's used to create a new object `finalObject` by merging two existing objects `firstObject` and `secondObject`. The spread operator uses the following syntax:

* `{ ... }`: This is the spread operator.
* `...objectLiteral`: This is the object being expanded.

**Pros of Using Spread Operator:**

* Concise code
* Easy to read and understand

**Cons of Using Spread Operator:**

* May not be supported in older browsers or environments (pre-ES2018).
* Can lead to unexpected behavior if not used carefully (e.g., when dealing with nested objects).

2. **Using `Object.assign()`**

`Object.assign()` is a built-in JavaScript method that returns a new object created by merging multiple source objects into one.

**Pros of Using `Object.assign`:**

* Widespread support across browsers and environments.
* More flexible than the spread operator, allowing you to specify which properties to merge.

**Cons of Using `Object.assign`:**

* Can be less concise than the spread operator.
* May require more boilerplate code (e.g., creating an empty object to merge into).

**Library or Special JS Feature: None**

There is no library or special JavaScript feature involved in this benchmark. The focus is solely on comparing the performance of two approaches.

**Other Considerations**

When working with objects and merging data, consider the following:

* Use `Object.assign()` when you need more control over which properties to merge.
* Use the spread operator when you need concise and readable code that's easy to understand.
* Be aware of potential pitfalls, such as nested objects or undefined values.

**Other Alternatives**

If you're looking for alternative approaches to merging objects in JavaScript, consider:

1. **Array.prototype.reduce()**: You can use `reduce()` to merge multiple objects into one.
```javascript
const finalObject = firstObject.reduce((acc, obj) => ({ ...acc, ...obj }), {});
```
2. **lodash's `_merge()` function**: If you're working with a large project or need more advanced merging functionality, consider using Lodash's `_merge()` function.
3. **`Object.create()`**: This method creates a new object that inherits properties from another object.

These alternatives offer different trade-offs in terms of conciseness, readability, and performance.

Related benchmarks:

JavaScript spread operator vs Object.assign performance (2) (version: 0)

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

Created: 4 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):