Benchmark: JavaScript spread operator vs Object.assign 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 gemma2:9b, generated one year ago):

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This benchmark tests the performance of two methods for combining JavaScript objects: the spread operator (`...`) and `Object.assign()`.

**Let's break down each method:**

* **Using the Spread Operator (`...`)**: This approach involves creating a new object literal and using the spread syntax to include properties from existing objects within it.  
    ```javascript
    const firstObject = { sampleData: 'Hello world' };
    const secondObject = { moreData: 'foo bar' };
    const finalObject = { ...firstObject, ...secondObject }; 
    ```

* **Using `Object.assign()`**: This method takes a target object and one or more source objects, copying properties from the sources into the target.  
    ```javascript
    const firstObject = { sampleData: 'Hello world' };
    const secondObject = { moreData: 'foo bar' };
    const finalObject = Object.assign({}, firstObject, secondObject); 
    ```

**Pros and Cons:**

* **Spread Operator:**
    * **Pros:** Concise and readable syntax. Often considered more intuitive for object merging.
    * **Cons:** Can be slightly slower than `Object.assign()`, especially with a large number of objects.

* **`Object.assign()`:** 
    * **Pros:** Generally faster than the spread operator, particularly with many source objects. More flexible as it allows you to specify the target object and modify existing properties. 
    * **Cons:** Syntax can be less intuitive compared to the spread operator.

**Other Considerations:**

* **Object Size:** The performance difference between these methods might be negligible for small objects. For very large objects, `Object.assign()` might offer a more noticeable speed advantage.
* **Readability:** Choose the method that makes your code easier to understand and maintain. If readability is paramount, the spread operator's simplicity might be preferred.

**Alternatives:**

While `Object.assign` and the spread operator are common methods for object merging, you could also consider using libraries like Lodash or Ramda, which provide specialized functions for object manipulation with potentially optimized performance.

Let me know if you have any more questions.

Related benchmarks:

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

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

Created: 8 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 gemma2:9b, generated one year ago):