Benchmark: obj test - MeasureThat.net

Script Preparation code:

const obj = { hello: 'world', foo: 'bar' }

Tests:

destructure and reassign
const other = {...obj, foo: 'not bar' };
just reassign
obj.foo = 'not bar'

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
destructure and reassign
just reassign

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 19 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
destructure and reassign	79413776.0 Ops/sec
just reassign	150571024.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 20 days ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON tests two different approaches to modifying an object's property in JavaScript: "destructure and reassign" vs. "just reassign."

### Options Compared

1. **Destructure and Reassign:**
   - **Benchmark Definition:** `const other = {...obj, foo: 'not bar' };`
   - In this approach, the object `obj` is copied into a new object `other` using the spread operator (`...`). The property `foo` is simultaneously reassigned to 'not bar', while keeping other properties intact.

2. **Just Reassign:**
   - **Benchmark Definition:** `obj.foo = 'not bar'`
   - In this method, the property `foo` of the existing object `obj` is directly reassigned to 'not bar'. This changes the original object without creating any new object.

### Pros and Cons

#### Destructure and Reassign (Using Spread Operator)
- **Pros:**
  - **Immutability:** This method creates a new object, which is often beneficial in functional programming paradigms where immutability is preferred. It can help prevent side effects since the original object remains unchanged.
  - **Clarity:** The intention of not mutating the original object can enhance code readability, making it clear that a new version of the object is created.

- **Cons:**
  - **Performance:** It can be more performance-intensive, as it involves both copying the object and creating a new reference. As evidenced by the benchmark results, this approach executed significantly fewer operations per second compared to the reassignment method.
  - **Overhead:** If an object's structure is complex or very large, this method may lead to more memory usage, as it creates a new object rather than modifying the original.

#### Just Reassign
- **Pros:**
  - **Performance:** This approach is faster, as shown in the benchmark results. It yields a higher number of executions per second, making it generally more efficient for simple property assignments.
  - **Memory Efficiency:** It directly modifies the existing object without needing additional memory for a new object.

- **Cons:**
  - **Mutability:** This method alters the original object, which could lead to unintended side effects, especially if other references to the object exist in the codebase. This can make debugging more difficult in larger applications.
  - **Reduced Clarity:** In environments where immutability is essential for maintaining state integrity (e.g., React), direct reassignment may be considered less desirable.

### Other Considerations

When choosing between these methods, developers should consider:
- **Codebase Standards:** If the project adheres to functional programming principles, destructive methods may be discouraged.
- **State Management Needs:** In UI frameworks, immutability can simplify state management and facilitate easier tracking of changes.
- **Performance Requirements:** For performance-sensitive applications, especially large-scale applications, minimizing overhead might take precedence.

### Alternatives

Other methods for updating an object's properties include:
- **Using `Object.assign()`:** This method returns a new object by copying properties from one or more source objects.
  ```javascript
  const other = Object.assign({}, obj, { foo: 'not bar' });
  ```
- **Using Immutable.js or similar libraries:** These libraries provide data structures that maintain immutability more effectively and may offer performance optimization for certain use cases.

In conclusion, the approach selected for modifying object properties largely depends on the specific requirements of the application being developed, balancing the trade-offs between performance, clarity, and mutability according to project standards and complexity.

Related benchmarks:

obj test (version: 1)

Comparing performance of: destructure and reassign vs just reassign

Created: 20 days ago by: Guest

Jump to the latest result

destructure and reassign

just reassign

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 20 days ago):