What is being tested?

The provided JSON represents a JavaScript microbenchmark, specifically testing the performance of three methods to create a shallow copy of an object:

1. Spread operator (...): This method creates a new object by spreading the properties of another object.
2. Object.assign(): This method creates a new object and copies the specified properties from an existing object into it.
3. Object.create(): This method creates a new object and copies all own enumerable properties from a given object (the prototype) to the new object.

The benchmark measures which approach is faster in terms of execution per second for each test case.

Options comparison

The main options being compared are:

• Spread operator (...): Creates a new object by spreading the properties of another object.
  • Pros:
    • Simple and concise syntax.
    • Fast and efficient, as it only copies the properties without modifying the original object.
  • Cons:
    • May not be suitable for deep objects or objects with complex property names, as it can lead to unexpected behavior.
• Object.assign(): Creates a new object and copies the specified properties from an existing object into it.
  • Pros:
    • Flexible and adaptable syntax, allowing you to specify which properties to copy.
    • Supports copying of nested objects using the { property: value } syntax.
  • Cons:
    • Can be slower than the spread operator due to additional overhead from checking the Object.assign() method's signature.
• Object.create(): Creates a new object and copies all own enumerable properties from a given object (the prototype) to the new object.
  • Pros:
    • More flexible than Object.assign(), as it allows you to set any property on the new object, not just those specified in the original object.
  • Cons:
    • Less intuitive syntax and may be harder to read for developers familiar with Object.assign().

Library usage

In this benchmark, none of the libraries are explicitly mentioned. However, it is worth noting that both Object.assign() and Object.create() rely on the JavaScript prototype chain, which is a fundamental concept in JavaScript.

Special JS feature or syntax

The spread operator (...) was introduced in ECMAScript 2015 (ES6) as a new way to create objects from existing objects. It has become a popular and efficient method for creating shallow copies of objects.

In the provided benchmark, the spread operator is used in the following test case:

const firstObject = { \r\n  \tsampleData: 'Hello world',\r\n\tsampleMethod: () => { return true; }\r\n};\r\nconst secondObject = {...firstObject};

Alternatives

Other alternatives for creating shallow copies of objects in JavaScript include:

• Using the JSON.parse(JSON.stringify(obj)) method, which can create a deep copy of an object by serializing it as JSON and then parsing it back into an object.
• Using a library like Lodash, which provides a cloneDeep() function for creating deep copies of objects.

However, these alternatives are generally slower and more memory-intensive than the methods being tested in this benchmark.