Benchmark: Complex assign vs destructure

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Tests:

Complex assign
const a = { foo: "bar", baz: true, quux: { a: [1, 2, 3], b: new Date() } } const b = Object.assign({}, a)
Complex destructure
const a = { foo: "bar", baz: true, quux: { a: [1, 2, 3], b: new Date() } } const b = { ...a }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Complex assign
Complex destructure

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:142.0) Gecko/20100101 Firefox/142.0

Browser/OS: Firefox 142 on Mac OS X 10.15

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Test name	Executions per second
Complex assign	14376036.0 Ops/sec
Complex destructure	11084123.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 8 months ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON tests two different approaches for creating a new object based on an existing object in JavaScript. The two techniques being compared are the use of `Object.assign` versus the object spread operator (`...`) for object cloning.

### Options Compared

1. **Complex Assign**: 
    - **Code**: `const b = Object.assign({}, a)`
    - **Description**: This method uses `Object.assign()` to create a shallow copy of the object `a`. A new empty object (`{}`) is passed as the target, and the properties from `a` are copied into it.

2. **Complex Destructure**: 
    - **Code**: `const b = { ...a }`
    - **Description**: This method utilizes the object spread operator, which is a more modern and concise syntax for shallow copying an object. It effectively spreads the keys and values of `a` into a new object.

### Pros and Cons

#### Object.assign
- **Pros**:
  - Widely supported in older JavaScript environments (ES5 and later).
  - Clear and explicit about copying properties.
  
- **Cons**:
  - Slightly more verbose compared to the spread operator.
  - May not be as intuitive at first glance for some developers, especially if they are not familiar with the `Object` methods.
  - Limited to shallow copying, meaning nested objects remain references to the same objects as in the original.

#### Object Spread Operator
- **Pros**:
  - More concise and readable, aligning with modern JavaScript syntax.
  - Encourages cleaner code and easier maintenance.
  - Also shallow copies properties, which is the same limitation as `Object.assign()`; however, its syntax may convey intent more clearly in contemporary codebases.
  
- **Cons**:
  - Requires ES6 (ES2015) support; older environments may not support the spread operator unless transpiled.
  - Similar limitations regarding nested objects – it does not perform deep cloning.

### Other Considerations
Both methods perform shallow copying, meaning that nested objects will still refer to the same objects in memory rather than creating full duplicates. If a deep copy is required, other libraries such as `lodash` with its `cloneDeep()` function or structured cloning techniques would need to be employed.

### Alternative Approaches
1. **Using `JSON.parse(JSON.stringify(a))`**:
   - This creates a deep copy by serializing the object to a JSON string and then parsing it back into an object. This method will not work for objects containing functions, `undefined`, or special object types (like `Date`, `Map`, `Set`).

2. **Libraries**:
   - Libraries like `lodash` or `ramda` provide various utility functions for object manipulation and can achieve deep copying and merging with more capabilities than native functions.

3. **Manual Deep Clone**:
   - Implementing a custom cloning function that recursively copies properties for complex objects can provide more control but requires careful consideration of all edge cases.

### Conclusion
This benchmark provides insight into the performance characteristics of two common methods for object cloning in JavaScript. The choice between `Object.assign()` and the spread operator should consider both performance outcomes from the benchmarks and the readability/maintainability of the code, particularly when working within larger teams or projects.

Related benchmarks:

Complex assign vs destructure (version: 1)

Comparing performance of: Complex assign vs Complex destructure

Created: 8 months ago by: Guest

Jump to the latest result

Complex assign

Complex destructure

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 8 months ago):