Benchmark: JavaScript spread dsfdsfsdfdsfasdfadsfoperator vs Object.assign performance

Tests:

Using the spread operator
"use strict"; function ownKeys(object, enumerableOnly) { var keys = Object.keys(object); if (Object.getOwnPropertySymbols) { var symbols = Object.getOwnPropertySymbols(object); if (enumerableOnly) symbols = symbols.filter(function (sym) { return Object.getOwnPropertyDescriptor(object, sym).enumerable; }); keys.push.apply(keys, symbols); } return keys; } function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i] != null ? arguments[i] : {}; if (i % 2) { ownKeys(Object(source), true).forEach(function (key) { _defineProperty(target, key, source[key]); }); } else if (Object.getOwnPropertyDescriptors) { Object.defineProperties(target, Object.getOwnPropertyDescriptors(source)); } else { ownKeys(Object(source)).forEach(function (key) { Object.defineProperty(target, key, Object.getOwnPropertyDescriptor(source, key)); }); } } return target; } function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; } var firstObject = { sampleData: 'Hello world' }; var secondObject = { moreData: 'foo bar' }; var finalObject = _objectSpread(_objectSpread({}, 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 llama3.2:3b, generated one year ago):

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**Overview**

The provided benchmark measures the performance of two approaches to merge objects: using the spread operator (`_objectSpread` function) and `Object.assign()`. The test creates two objects, `firstObject` and `secondObject`, with some sample data. It then uses these objects to create a final object using both methods.

**Test Setup**

The test code is as follows:
```javascript
var firstObject = {
  sampleData: 'Hello world'
};

var secondObject = {
  moreData: 'foo bar'
};

var finalObject = _objectSpread(_objectSpread({}, firstObject), secondObject);
```
For the `Object.assign()` approach, the test code is as follows:
```javascript
const firstObject = { sampleData: 'Hello world' }

const secondObject = { moreData: 'foo bar' }

const finalObject = Object.assign(firstObject, secondObject);
```
**Library and Features**

* `_objectSpread` function: This is a custom function that uses the spread operator to merge objects. It's not part of the standard JavaScript library.
* `Object.assign()`: This is a built-in method in the JavaScript standard library, introduced in ECMAScript 2015 (ES6). It allows you to copy properties from one or more source objects to a target object.

**Options Compared**

The test compares two options:

1. **Using the spread operator (`_objectSpread` function)**: This approach uses the spread operator to merge the objects. The `_objectSpread` function takes three arguments: the target object, and two source objects. It returns a new object with the merged properties.
2. **Using `Object.assign()`**: This approach uses the built-in `Object.assign()` method to merge the objects. It takes one or more source objects as arguments and returns a new object with the merged properties.

**Pros and Cons**

* Using the spread operator (`_objectSpread` function):
	+ Pros:
		- More concise and readable code.
		- No need to worry about property order or merging duplicate properties.
	+ Cons:
		- May have slower performance due to its implementation details.
* Using `Object.assign()`:
	+ Pros:
		- Faster performance, as it's implemented in native code.
		- More control over the merging process, as you can specify the property order and handling of duplicate properties.
	+ Cons:
		- Less concise and readable code.

**Other Considerations**

* Performance: The test results show that `Object.assign()` is faster than the spread operator approach. However, this may vary depending on the specific use case and JavaScript engine used.
* Code readability: The spread operator approach is generally more readable and concise, while `Object.assign()` requires more boilerplate code.

**Alternatives**

If you need to merge objects in a performance-critical path, you could consider using other libraries or modules that provide optimized merging functionality, such as:

* Lodash's `_.merge()`
* Underscore.js's `_merge()`
* A custom implementation using bitwise operators and array manipulation techniques.

However, for most use cases, the spread operator approach is a good choice due to its conciseness and readability.

Related benchmarks:

JavaScript spread dsfdsfsdfdsfasdfadsfoperator vs Object.assign performance (version: 0)

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

Created: 5 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 llama3.2:3b, generated one year ago):