What is tested?

MeasureThat.net is testing the performance of two different methods for creating a shallow copy of an object in JavaScript: the spread operator (...) and Object.assign(). The benchmark is measuring how fast each method can create a new object with some of the properties from an existing object.

Options compared

There are two options being compared:

1. Spread operator (...): This method creates a new object by iterating over the properties of the original object and adding them to the new object using the spread operator.
2. Object.assign(): This method creates a new object by copying the properties from an existing object.

Pros and cons

• Spread operator (...):
  • Pros: concise, readable, and easy to understand for most developers.
  • Cons: may not be as efficient as Object.assign() in older browsers or environments where support is limited.
• Object.assign():
  • Pros: widely supported across different browsers and environments, can handle more complex cases such as arrays and objects with functions.
  • Cons: less readable than the spread operator for some developers.

Other considerations:

• The benchmark does not account for other factors that might affect performance, such as object size or complexity. For example, if the original object is very large, Object.assign() may perform better due to its ability to handle arrays and objects with functions.
• The benchmark does not consider security implications. For example, using Object.assign() with an untrusted source can lead to security vulnerabilities.

Libraries and special JS features

In this benchmark, no libraries are used beyond the standard JavaScript features. However, it's worth noting that in other cases, MeasureThat.net may use additional libraries or features, such as async/await for handling asynchronous operations.

No special JavaScript features are used in this specific benchmark.

Other alternatives

If you want to create a shallow copy of an object in JavaScript, there are other methods available:

• Object.assign() with an empty object: const finalObject = Object.assign({}, secondObject);
• Array.prototype.slice() and Array.prototype.concat(): const finalObject = { ...secondObject }; (not exactly the same as the spread operator, but achieves similar results)
• JSON.parse(JSON.stringify()): Not recommended due to its complexity and potential security risks.

Keep in mind that each of these alternatives has its own trade-offs and may not be suitable for all use cases. The spread operator (...) is generally considered the most modern and efficient way to create a shallow copy of an object in JavaScript.