Benchmark: assign vs spread 196987356211

Tests:

assign
const obj = { a: 'asdfasdfasd', b:'sdafasdfasdgdafgasdfasdf' } const copy = Object.assign({}, obj)
spread
const obj = { a: 'asdfasdfasd', b:'sdafasdfasdgdafgasdfasdf' } const copy = { ...obj }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
assign
spread

Fastest: N/A

Slowest: N/A

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

The provided benchmark definition json and individual test cases indicate that we're comparing two approaches to create a shallow copy of an object in JavaScript:

1. **Object.assign()**: This method creates a new object with the same properties as the source object. The source object is spread into the new object, allowing you to use its own syntax for creating copies.

```javascript
const obj = { a: 'asdfasdfasd', b:'sdafasdfasdgdafgasdfasdf' };
const copy = Object.assign({}, obj);
```

2. **Destructuring assignment (Spread operator)**: This approach creates a new object with the same properties as the source object. The spread operator (`{ ...obj }`) is used to create an object from the existing one.

```javascript
const obj = { a: 'asdfasdfasd', b:'sdafasdfasdgdafgasdfasdf' };
const copy = { ...obj };
```

Pros and Cons:

- **Object.assign()**:
  - Pros: Can be used with arrays, objects, or even custom objects. It's also quite fast because it doesn't create a new object.
  - Cons: Returns an object, which might not always be what you want. It can also mutate the original object if the source is modified.

- **Destructuring assignment (Spread operator)**:
  - Pros: Creates an exact copy of the original object without mutating it. It's quite intuitive and commonly used in modern JavaScript.
  - Cons: Can't be used with arrays; it's meant for objects only. Also, like `Object.assign()`, it can mutate the source if modified.

Other considerations:

- **Performance**: In general, using spread operator is faster because it doesn't create an intermediate object. However, this difference might not be noticeable in most use cases.
- **Readability and maintainability**: Using a spread operator makes your code more concise and readable, especially when dealing with objects that have many properties.

Library/Function Used:

None are explicitly mentioned, but `Object.assign()` is a standard JavaScript method.

Special JS Feature/Syntax:

The spread operator (`{ ...obj }`) uses the rest parameter syntax (which was introduced in ECMAScript 2015) to create an object from another object. This feature allows you to use it with objects and arrays only.

Alternatives:

- **Lodash's `cloneDeep()`**: Lodash, a popular JavaScript utility library, provides a function called `cloneDeep()` which creates a deep copy of a value.
- **JSON.parse(JSON.stringify(obj))**: However, this approach creates a deep object clone but doesn't work with custom objects that don't support JSON serialization.

In summary, the choice between these two methods depends on your needs. If you want to create an exact, non-mutating copy of an object and prefer modern syntax, use the spread operator. If you need to create copies from arrays or have control over how objects are cloned, consider using `Object.assign()`.

Related benchmarks:

assign vs spread 196987356211 (version: 0)

Comparing performance of: assign vs spread

Created: 7 years ago by: Guest

Jump to the latest result

assign

spread

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):