Measuring the performance of different approaches to create and update objects in JavaScript can be a fascinating benchmark. Let's break down what is tested on the provided JSON:

The test creates an object data with 100 properties, each representing an item with an ID, name, and value. The goal is to add a new item to the items array without modifying the original object.

Three approaches are compared:

1. Immer: Immer is a library that provides a safe way to work with immutable data structures. In this test, immer.default is used to create a draft of the data object and then update it with a new item.
   • Pros:
     • Ensures immutability of the original object, which can be beneficial for concurrent programming or when working with shared data.
     • Reduces side effects by creating a new object instead of modifying an existing one.
   • Cons:
     • Can be slower than other approaches due to the overhead of creating and managing draft objects.
2. Shallow Copy: This approach creates a shallow copy of the data object using the spread operator ({ ...data, ... }) and then updates it with the new item.
   • Pros:
     • Faster than Immer since it doesn't involve creating draft objects or managing immutability.
     • More lightweight compared to Immer.
   • Cons:
     • Modifies the original object, which can lead to unexpected behavior if other parts of the code rely on its immutability.
3. Immutable: This approach uses Immutable.js to create a new immutable object from the data object and then updates it with the new item using methods like set().
   • Pros:
     • Ensures immutability, similar to Immer.
     • Can be more efficient than Shallow Copy since Immutable.js optimizes memory allocation and garbage collection.
   • Cons:
     • Requires additional dependencies (Immutable.js) and can add overhead due to the need for explicit object creation.

The test case uses new Date() instead of a special JS feature or syntax, which is a common practice in benchmarking to ensure consistent results across different browsers and environments.

The latest benchmark result shows that Shallow Copy outperforms both Immer and Immutable.js, likely due to its lightweight nature and lack of overhead. However, the actual performance difference may vary depending on the specific use case and requirements.

Other alternatives to consider:

• Object.assign(): This method creates a new object by copying an existing one and then updates it with the new item.
  • Pros: Simple and efficient, but may not be as lightweight as Shallow Copy or Immutable.js.
  • Cons: Modifies the original object if not used carefully.
• Proto-based approach: Some developers might use prototype chains to create a new object by extending an existing one. However, this approach can lead to unexpected behavior and is generally discouraged in favor of more explicit and predictable methods like Immer or Immutable.js.

Keep in mind that the choice of approach ultimately depends on your specific requirements, such as performance, readability, and maintainability.