How can I achieve deep object comparison in JavaScript Sets?

Customizing Object Equality for JavaScript Set

The ES6 Set object uses reference equality to determine object equality, which may not be suitable for comparing objects with the same values but different references. To address this issue, we explore the need for customizing equality for Set objects in order to achieve deep object comparison.

Unfortunately, the ES6 Set object does not currently offer any methods or extensibility to customize its comparison algorithm. The .has(), .add(), and .delete() methods solely rely on object or primitive value reference comparisons.

While it is possible to create a custom object derived from Set and redefine the .has(), .add(), and .delete() methods to implement deep object comparison logic, this approach would negatively impact performance due to the computationally intensive brute force iteration required to find matches before invoking the original .add() method.

As discussed in an ES6 feature article, the implementation of customizable key and value comparison in maps and sets has been postponed due to challenges in maintaining efficiency and handling mutable objects. The proposal suggests using callbacks for specifying equality or adopting an approach similar to Java's equals() method, which relies on immutable objects (value objects) for value-based comparisons. However, this latter approach poses challenges when dealing with mutable objects, as changes in an object's contents would necessitate adjustments to its location within a collection.

Currently, there is a proposal to include Records and Tuples in JavaScript. These immutable data structures support direct value-based comparison using === or !==. Additionally, the proposal suggests using Record and Tuple values as keys in Set and Map objects, effectively addressing the original problem of deep object comparison in Sets. This proposal is still in development and subject to further refinement and adoption.

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