Benchmark: JavaScript spread operator vs Object.assign performancee

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 dive into the world of JavaScript microbenchmarks on MeasureThat.net.

The provided benchmark definition and test cases focus on comparing the performance of two approaches: using the spread operator (`...`) to merge objects, and using `Object.assign()` to achieve the same result.

**Spread Operator Approach**

In this approach, we create two example objects: `firstObject` and `secondObject`. We then use the spread operator (`...`) to merge these objects into a new object, `finalObject`.

```javascript
const firstObject = { sampleData: 'Hello world' };
const secondObject = { moreData: 'foo bar' };
const finalObject = {
  ...firstObject,
  ...secondObject
};
```

**Object.assign() Approach**

In this approach, we also create the same two example objects. However, instead of using the spread operator, we use `Object.assign()` to merge these objects into a new object.

```javascript
const firstObject = { sampleData: 'Hello world' };
const secondObject = { moreData: 'foo bar' };
const finalObject = Object.assign({}, firstObject, secondObject);
```

**Pros and Cons of Each Approach**

* **Spread Operator Approach:**
	+ Pros:
		- More concise and readable syntax.
		- No need to specify the order of properties.
	+ Cons:
		- May not be as efficient for large objects, as it creates a new object with shallow copies of the properties.
		- Not supported in older browsers (e.g., Internet Explorer).
* **Object.assign() Approach:**
	+ Pros:
		- More efficient for large objects, as it creates an entirely new object without copying properties.
		- Supported by all modern browsers and JavaScript engines.
	+ Cons:
		- Less readable syntax, especially when dealing with nested objects.
		- Requires specifying the order of properties.

**Library Used:**

There is no explicit library mentioned in the benchmark definition. However, `Object.assign()` is a built-in method in JavaScript, so no additional libraries are required for this test case.

**Special JS Feature/Syntax:**

The spread operator (`...`) was introduced in ECMAScript 2015 (ES6). It allows you to merge objects by spreading their properties into a new object. This syntax is also supported by most modern browsers and JavaScript engines.

**Other Alternatives:**

For merging objects, other approaches exist, such as:

* Using the `merge()` method from the `lodash` library.
* Using the `reduce()` method to concatenate objects.
* Using a custom implementation with loops and object iteration.

However, the spread operator approach and `Object.assign()` approach are two of the most widely used and efficient methods for merging objects in modern JavaScript.

Related benchmarks:

JavaScript spread operator vs Object.assign performancee (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):