Benchmark: JavaScript spread operator vs Object.assign wrapper performance

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const update = (first, ...args) => { return Object.assign({}, first, ...args) } const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = update(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:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Android 13; Mobile; rv:136.0) Gecko/136.0 Firefox/136.0

Browser/OS: Firefox Mobile 136 on Android

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Test name	Executions per second
Using the spread operator	7391873.5 Ops/sec
Using Object.assign	5604231.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**Benchmark Overview**

The benchmark measures the performance of two approaches for merging objects: using the spread operator (`...`) and using `Object.assign()`. The goal is to determine which approach is faster.

**Options Compared**

Two options are compared:

1. **Using the Spread Operator (`...`)**: This method uses the spread operator to merge two objects into a new object. The syntax is:
```javascript
const finalObject = { ...firstObject, ...secondObject };
```
2. **Using `Object.assign()`**: This method uses the `Object.assign()` function to merge two objects into a new object. The syntax is:
```javascript
const update = (first, ...args) => {
  return Object.assign({}, first, ...args);
};

const finalObject = update(firstObject, secondObject);
```
**Pros and Cons of Each Approach**

1. **Using the Spread Operator (`...`)**:
	* Pros: More concise and readable syntax.
	* Cons: May not be supported in older browsers or Node.js versions.
2. **Using `Object.assign()`**:
	* Pros: Widely supported, including older browsers and Node.js versions.
	* Cons: Longer syntax and may require more boilerplate code.

**Other Considerations**

When choosing between these approaches, consider the following:

* Code readability: If conciseness is important, using the spread operator might be a better choice. However, if you need to ensure compatibility with older browsers or Node.js versions, `Object.assign()` might be a safer option.
* Performance: Both approaches have similar performance characteristics, as they both create a new object and copy the properties from the source objects.

**Library and Special JS Feature**

There are no libraries used in this benchmark. However, the use of spread operator (`...`) is a modern JavaScript feature introduced in ECMAScript 2018 (ES2018). If you're targeting older browsers or Node.js versions, you may need to use `Object.assign()` instead.

**Alternative Approaches**

Other alternatives for merging objects include:

1. **Loose Equality Operator (`==`)**: This approach uses loose equality operator to merge properties, but it can lead to unexpected results if the property names are not exactly the same.
2. **JSON Merge Patch**: This approach uses a library like json-merge-patch to merge two objects. It's a more robust and flexible way to handle object merges, especially when dealing with nested objects.

In summary, the benchmark measures the performance of two approaches for merging objects: using the spread operator (`...`) and using `Object.assign()`. While both approaches have similar performance characteristics, using the spread operator is generally considered more concise and readable.

Related benchmarks:

JavaScript spread operator vs Object.assign wrapper performance (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

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