Benchmark: JavaScript spread operator vs Object.assign 2

Script Preparation code:

var firstObject = Array.from({ length: 100 }).reduce((acc, _el, index) => {
  acc[`some_${index}`] = index; 
  return acc;
}, {});
var secondObject = Array.from({ length: 100 }).reduce((acc, _el, index) => {
  acc[`some_other_${index}`] = index; 
  return acc;
}, {});

Tests:

Using the spread operator
const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
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

Latest run results:

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

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Let's break down the provided JSON and explain what is being tested, the options compared, their pros and cons, and other considerations.

**Benchmark Definition**

The benchmark definition provides two script preparation codes that create identical objects, `firstObject` and `secondObject`. These objects have 100 properties each, where each property has a unique key (e.g., `some_0`, `some_1`, etc.). The script preparation code is the same for both objects.

**Script Preparation Code**
```javascript
var firstObject = Array.from({ length: 100 }).reduce((acc, _el, index) => {
  acc[`some_${index}`] = index;
  return acc;
}, {});

**Html Preparation Code**

There is no HTML preparation code provided, which means that the benchmark is purely JavaScript-based and does not involve rendering any HTML or CSS.

**Individual Test Cases**

The benchmark consists of two test cases:

1. **Using the spread operator**
```javascript
const finalObject = { ...firstObject, ...secondObject };
```
This test case uses the spread operator (`...`) to merge the two objects into a single object.

2. **Using Object.assign**
```javascript
const finalObject = Object.assign({}, firstObject, secondObject);
```
This test case uses `Object.assign()` to create a new object and merge the properties from `firstObject` and `secondObject`.

**Options Compared**

The benchmark compares two options:

1. Using the spread operator (`...`)
2. Using `Object.assign()`

**Pros and Cons of Each Approach**

1. **Using the spread operator**
	* Pros:
		+ More concise and expressive syntax.
		+ Allows for easier creation of shallow copies of objects.
	* Cons:
		+ Can be slower due to the overhead of creating a new object.
2. **Using Object.assign()**
	* Pros:
		+ Faster than using the spread operator, as it avoids creating a new object.
	* Cons:
		+ Requires explicit creation of an empty object (`Object.assign({}, ...)`).
		+ Less concise and expressive syntax.

**Other Considerations**

The benchmark does not consider other factors that might affect performance, such as:

* Array size: The benchmark assumes 100 elements for both objects. Increasing the array size would likely impact performance.
* Property names: Using shorter property names or more complex property names could affect performance.
* Browser versions and platforms: Different browsers and platforms may have varying performance characteristics.

**Library Used**

In this case, no specific library is used beyond the built-in `Array.prototype.reduce()` method and `Object.assign()` function.

**Special JS Feature or Syntax**

The benchmark uses the spread operator (`...`), which was introduced in ECMAScript 2015 (ES6). This syntax allows for concise creation of shallow copies of objects.

Related benchmarks:

JavaScript spread operator vs Object.assign 2 (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):