Benchmark: JavaScript create new Object with properties. Equal operator vs Object.assign performance

Tests:

Using the Object.assign
let firstObject = Object.assign({}, { sampleData: 'Hello world', sampleData0: 'Hello world 0', sampleData1: 'Hello world 1', sampleData2: 'Hello world 2', sampleData3: 'Hello world 3', sampleData4: 'Hello world 4', sampleData5: 'Hello world 5', sampleData6: 'Hello world 6', sampleData7: 'Hello world 7', }); let secondObject = Object.assign({}, { sampleData: 'foo bar', sampleData0: 'Hello world 0', sampleData1: 'Hello world 1', sampleData2: 'Hello world 2', sampleData3: 'Hello world 3', sampleData4: 'Hello world 4', sampleData5: 'Hello world 5', sampleData6: 'Hello world 6', sampleData7: 'Hello world 7', });
Using the equal operator
let firstObject = { sampleData: 'Hello world' }; let secondObject = { moreData: 'foo bar' }; firstObject.sampleData0 = 'Hello world 0'; firstObject.sampleData1 = 'Hello world 1'; firstObject.sampleData2 = 'Hello world 2'; firstObject.sampleData3 = 'Hello world 3'; firstObject.sampleData4 = 'Hello world 4'; firstObject.sampleData5 = 'Hello world 5'; firstObject.sampleData6 = 'Hello world 6'; firstObject.sampleData7 = 'Hello world 7'; secondObject.sampleData0 = '0 Hello world'; secondObject.sampleData1 = '1 Hello world'; secondObject.sampleData2 = '2 Hello world'; secondObject.sampleData3 = '3 Hello world'; secondObject.sampleData4 = '4 Hello world'; secondObject.sampleData5 = '5 Hello world'; secondObject.sampleData6 = '6 Hello world'; secondObject.sampleData7 = '7 Hello world';

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the Object.assign
Using the equal operator

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 23 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what is tested, compared options, pros/cons of those approaches, and other considerations.

**Benchmark Definition**

The benchmark measures the performance difference between using the `Object.assign()` method to create a new object with properties versus using the equality operator (`==`) to assign values to existing object properties.

**Test Cases**

There are two test cases:

1. **Using the Object.assign()**: This test case creates an initial object `firstObject` with 8 properties, and then uses `Object.assign()` to create a new object `secondObject` that has some of the same properties as `firstObject`. The test then iterates over 7 values (from 0 to 6) and assigns each value to a corresponding property on both objects. Finally, it checks if the assigned values are equal using the equality operator (`==`).
2. **Using the equal operator**: This test case creates two separate objects `firstObject` and `secondObject`. Then, it iterates over 7 values (from 0 to 6) and assigns each value to a corresponding property on both objects. Finally, it checks if the assigned values are equal using the equality operator (`==`).

**Comparison**

The comparison between these two approaches is:

* **Object.assign()**: Creates a new object with properties, which can be useful when you need to create a copy of an existing object or merge multiple objects into one.
* **Equality operator (`==`)**: Assigns values to existing object properties, which can lead to unexpected behavior if the original property values are changed.

**Pros and Cons**

**Object.assign()**:

Pros:

* Creates a new object with distinct property names, which can be useful for readability and maintainability.
* Can handle nested objects and arrays.

Cons:

* Requires creating an initial object, which can have performance implications (more on this later).
* May not be as efficient as assigning values to existing properties using the equality operator.

**Equality operator (`==`)**:

Pros:

* Assigns values to existing properties without creating a new object, which can be faster.
* Does not require creating an initial object.

Cons:

* Can lead to unexpected behavior if the original property values are changed.
* May not be as readable or maintainable than using `Object.assign()`.

**Other Considerations**

* **Performance**: Creating an initial object with 8 properties and then assigning values using `Object.assign()` may have performance implications, especially if the object is large. Assigning values to existing properties using the equality operator might be faster.
* **Memory usage**: Using `Object.assign()` creates a new object, which can lead to increased memory usage. Assigning values to existing properties using the equality operator does not create a new object.
* **Readability and maintainability**: Using `Object.assign()` can make code more readable and maintainable by avoiding changes to original property values.

**Alternative approaches**

Other alternatives for creating objects with properties include:

* **`Object.create()`**: Creates an object with a given prototype, which can be useful when you need to create an object with a specific inheritance hierarchy.
* **`Array.prototype.reduce()`**: Can be used to create an object by reducing an array of key-value pairs.

In conclusion, the benchmark highlights the trade-offs between using `Object.assign()` and the equality operator for creating objects with properties. While `Object.assign()` provides readability and maintainability benefits, it may come at a performance cost. Assigning values to existing properties using the equality operator can be faster but may lead to unexpected behavior if original property values are changed.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.1.2 Safari/605.1.15

Browser/OS: Safari 14 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Using the Object.assign	1745125.1 Ops/sec
Using the equal operator	124910584.0 Ops/sec

Related benchmarks:

JavaScript create new Object with properties. Equal operator vs Object.assign performance (version: 0)

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

Created: 5 years ago by: Guest

Jump to the latest result

Using the Object.assign

Using the equal operator

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 23 days ago):