Let's break down what's being tested in this benchmark and compare the different approaches.

Benchmark Definition

The benchmark is designed to measure the performance difference between two ways of merging objects in JavaScript: using the spread operator (...) and Object.assign() with a new object.

Options Compared

There are two options compared:

1. Using the Spread Operator: This approach uses the ... operator to merge two objects into a new one.

const finalObject = { ...firstObject, ...secondObject };

2. Using Object.assign() with a New Object: This approach uses the Object.assign() method to merge two objects into a new one, but creates a new object as an intermediate step.

const finalObject = Object.assign({}, firstObject, secondObject);

Pros and Cons

• Using the Spread Operator:
  • Pros: concise and expressive syntax, efficient performance (as it avoids creating a new object).
  • Cons: may not be immediately clear to developers without experience with this feature.
• Using Object.assign() with a New Object:
  • Pros: more explicit and maintainable code, easier to understand for developers without experience with the spread operator.
  • Cons: creates an intermediate object, which can lead to increased memory usage.

Library

There is no specific library being tested in this benchmark. However, Object.assign() is a built-in method of the JavaScript Object prototype.

Special JS Feature/Syntax

The use of the spread operator (...) is a special feature introduced in ECMAScript 2018 (ES2018). It allows objects to be expanded into new objects.

Other Alternatives

There are other ways to merge objects in JavaScript, such as using the merge() method from the lodash library or creating an object using the { ... } syntax and then updating its properties. However, these alternatives are not being tested in this benchmark.

In summary, the benchmark is testing two approaches for merging objects in JavaScript: using the spread operator (...) and Object.assign() with a new object. The results show that both approaches have similar performance characteristics, but the spread operator is more concise and efficient.