Benchmark: Object.assign-vs-Spread

Tests:

Object.assign
const acc= {a : [2]}; const newValue = { b: [3]}; Object.assign(acc, newValue); return acc
spread operator
const acc= {a : [2]}; const newValue = { b: [3]}; return { ...acc, ...newValue };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.assign
spread operator

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.86 Safari/537.36

Browser/OS: Chrome 73 on Mac OS X 10.14.3

View result in a separate tab

Test name	Executions per second
Object.assign	4369326.5 Ops/sec
spread operator	3998365.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks and explore what's being tested in this specific benchmark.

**Benchmark Overview**

The benchmark is designed to compare two approaches for copying an object in JavaScript: `Object.assign()` and the spread operator (`...`). The test case involves creating an object with a nested array, assigning a new value to another property, and then measuring which approach is faster.

**Options Compared**

In this benchmark, we have two options being compared:

1. **`Object.assign()`**: This method is used to copy properties from one or more source objects into the specified destination object.
2. **Spread Operator (`...`)**: This operator allows you to create a new object by spreading the properties of an existing object.

**Pros and Cons**

Here are some pros and cons for each approach:

**`Object.assign()`**

Pros:

* Wide support across browsers and Node.js versions
* Easy to use and understand

Cons:

* Can lead to shallow copying, which may not be suitable for complex objects with circular references or functions as properties
* May have performance implications due to the way it's implemented under the hood

**Spread Operator (`...`)**

Pros:

* Creates a deep copy of the object, including all nested arrays and objects
* Can be more efficient than `Object.assign()` in some cases

Cons:

* Not supported in older browsers or Node.js versions (e.g., Internet Explorer 11 and earlier)
* May have performance implications due to the way it's implemented under the hood

**Other Considerations**

In addition to these two options, there are other ways to copy objects in JavaScript, such as using `JSON.parse(JSON.stringify(obj))` or a library like Lodash. However, these methods may not be as efficient or scalable as `Object.assign()` and the spread operator.

**Library: `Lodash` (optional)**

In some test cases, you might see libraries like Lodash being used to implement functions that are not part of the JavaScript standard library. For example:
```javascript
const _ = require('lodash');
const acc = _.cloneDeep({a: [2]});
const newValue = { b: [3]};
acc = _.merge(acc, newValue);
return acc;
```
In this case, Lodash is being used to provide a more efficient and scalable implementation of the `merge()` function.

**Special JS Features or Syntax**

There are no special JavaScript features or syntax mentioned in this benchmark. However, it's worth noting that some newer browsers like Chrome 84+ and Node.js 14+ support additional features like `Object.assign()` with custom comparators.

**Other Alternatives**

If you're looking for alternative ways to copy objects in JavaScript, here are a few options:

* Using `JSON.parse(JSON.stringify(obj))`
* Creating a new object using the `{...obj}` syntax (introduced in ECMAScript 2015)
* Using a library like Lodash or underscore.js

Keep in mind that each of these alternatives has its own pros and cons, and some may be more suitable for specific use cases than others.

Related benchmarks:

Object.assign-vs-Spread (version: 0)

Comparing performance of: Object.assign vs spread operator

Created: 5 years ago by: Guest

Jump to the latest result

Object.assign

spread operator

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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