Benchmark: JavaScript spread operator vs Object.assign performance vs Multiple statementd

Tests:

Using the spread operator
let firstObject = { sampleData: 'Hello world' } const secondObject = { sampleData: 'Overwritten', moreData: 'foo bar' } firstObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { sampleData: 'Overwritten', moreData: 'foo bar' } Object.assign(firstObject, secondObject);
Multiple statements
const firstObject = { sampleData: 'Hello world' } const secondObject = { sampleData: 'Overwritten', moreData: 'foo bar' } firstObject.sampleData = secondObject.sampleData; firstObject.moreData = secondObject.moreData;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign
Multiple statements

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):

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Let's break down this benchmark test case by case.

**Benchmark Definition:**
The benchmark compares three different ways to update an object in JavaScript:

1. Using the spread operator (`...`)
2. Using `Object.assign()`
3. Updating properties individually using multiple statements

**Individual Test Cases:**

### 1. **Using the spread operator**

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

In this test case, we're using the spread operator (`...`) to merge `secondObject` into `firstObject`. The spread operator is a feature of JavaScript that allows us to expand an array or object into a new one. In this case, it's used to update the properties of `firstObject` with those from `secondObject`.

**Library/Feature:** None

**Pros/Cons:**

* Pros:
	+ Concise and expressive syntax
	+ Easy to read and write
* Cons:
	+ Can be slower than other methods for large objects (as shown in the benchmark results)

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

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

In this test case, we're using the `Object.assign()` method to update `firstObject` with properties from `secondObject`. This method creates a new object by copying the values of one or more objects.

**Library/Feature:** `Object.assign()`, which is a standard JavaScript method

**Pros/Cons:**

* Pros:
	+ Fast and efficient, especially for large objects
	+ Easy to use and understand
* Cons:
	+ Can be slower than other methods when used with small objects (as shown in the benchmark results)

### 3. **Multiple statements**

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

In this test case, we're updating `firstObject` by setting each property individually using assignment (`=`). This method is simple and easy to understand but can be slower than other methods.

**Library/Feature:** None

**Pros/Cons:**

* Pros:
	+ Simple and easy to read
	+ Can be faster than spread operator for small objects (as shown in the benchmark results)
* Cons:
	+ More verbose than other methods, which can make it harder to read and write

**Benchmark Results:**
The latest benchmark results show that:

* Multiple statements are the fastest method (34334988.0 executions per second)
* Object.assign() is slower than multiple statements but faster than the spread operator
* The spread operator is the slowest method among the three

**Alternatives:**

If you need to update an object with properties from another, consider using `Object.assign()` or a library like Lodash's `assign()` function. If performance is crucial and your objects are small, multiple statements might be a good choice.

Keep in mind that these results may vary depending on the specific JavaScript engine, browser, or environment you're using.

Related benchmarks:

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

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

Created: 5 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

Multiple statements

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):