Benchmark: JavaScript spread operator vs Object.assign performance (corrected)

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...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

Latest run results:

No previous 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 benchmark and explain what's being tested, compared, and the pros/cons of each approach.

**Benchmark Definition**

The benchmark is comparing two ways to merge objects in JavaScript: using the spread operator (`...`) and `Object.assign()`. The goal is to determine which method is faster for a simple object merging task.

**Options Compared**

1. **Using the spread operator**: This method uses the spread operator (`...`) to create a new object with the properties from both `firstObject` and `secondObject`.
2. **Using Object.assign()**: This method uses the `Object.assign()` function to create a new object by copying properties from two existing objects.

**Pros and Cons**

* **Using the spread operator**:
	+ Pros: Easy to read and write, concise syntax.
	+ Cons: Only supported in modern browsers (ECMAScript 2018+) and may not work in older browsers or environments that don't support the spread operator.
* **Using Object.assign()**:
	+ Pros: Widely supported across different browsers and environments, no dependencies required.
	+ Cons: May require more code to achieve the same result (e.g., creating an empty object `{}` before assigning properties).

**Library Used**

None. This benchmark doesn't rely on any external libraries.

**Special JS Feature or Syntax**

The spread operator (`...`) is a new feature introduced in ECMAScript 2018+. If you're using an older browser or environment, this method might not work as expected.

**Benchmark Preparation Code and Individual Test Cases**

The provided JSON defines two test cases:

1. Using the spread operator: This code snippet demonstrates how to use the spread operator to merge `firstObject` and `secondObject`.
2. Using Object.assign(): This code snippet shows how to use `Object.assign()` to merge `firstObject` and `secondObject`.

**Latest Benchmark Result**

The latest benchmark results compare the execution times of both methods on a Chrome 67 browser running on a Windows desktop.

* Using the spread operator: 1,810,151 executions per second.
* Using Object.assign(): 1,223,895 executions per second.

These results suggest that using the spread operator is slightly faster than using `Object.assign()` in this specific benchmark. However, it's essential to note that these results may vary depending on the browser, environment, and other factors.

**Other Alternatives**

If you need to merge objects in JavaScript, there are a few alternative approaches:

* Using the `{...}` syntax with an empty object: `const finalObject = { ...{}, ...firstObject, ...secondObject };`
* Using `Array.prototype.reduce()`: `finalObject = firstObject.reduce((acc, current) => ({ ...acc, ...current }), secondObject)`
* Using a library like Lodash's `merge()` function
* Manual property assignment: `const finalObject = {}; finalObject.sampleData = firstObject.sampleData; finalObject.moreData = secondObject.moreData;`

Keep in mind that each of these alternatives has its own trade-offs and may not be suitable for all use cases.

Related benchmarks:

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

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

Created: 7 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):