Benchmark: JavaScript spread operator vs Object.assign performance2

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 compares two methods for combining JavaScript objects:  the spread operator (`...`) and `Object.assign()`.

**Here's a breakdown:**

* **Spread Operator (`...`)**: This syntax takes the values from an object and expands them individually. In this case, it creates a new object containing all properties from `firstObject` followed by all properties from `secondObject`.

```javascript
   const finalObject = {
       ...firstObject, 
       ...secondObject
   };
   ```

* **`Object.assign()`**: This method copies the enumerable properties of one or more source objects to a target object.

```javascript
   const finalObject = Object.assign({}, firstObject, secondObject);
   ```

**Pros and Cons:**

* **Spread Operator:**
    * **Pros:** More concise and often considered more readable.
    * **Cons:** Can be less performant for very large objects due to how it iterates through properties. 
* **`Object.assign()`**:
    * **Pros:** Generally more performant for larger objects, as it's optimized for copying properties efficiently.
    * **Cons:** Less concise syntax compared to the spread operator.

**Other Considerations:**

* **Performance Trade-offs:** The benchmark results show that `Object.assign()` is faster in this specific case. However, the performance difference may not be significant in most real-world scenarios.

* **Code Readability:** The spread operator often leads to more readable and maintainable code for simple object merging tasks.

**Alternatives:**

While these are the two primary methods, there are other approaches:

* **Manual Object Merging:** You can write your own loop-based logic to iterate through objects and copy properties. This gives you maximum control but can be less concise.
* **Libraries/Utilities:**  JavaScript libraries like Lodash or Ramda offer helper functions for object merging with various options and optimizations.

Related benchmarks:

JavaScript spread operator vs Object.assign performance2 (version: 0)

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

Created: 7 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):