How to customize object equality in JavaScript Sets for deep comparisons?

Customization of Object Equality in JavaScript Sets

Context:
In JavaScript's ES6 Set object, equality is determined by the === operator, which compares object references. This approach is not suitable for comparing objects deeply.

Question:
How can we customize object equality in Set objects to enable deep object comparisons similar to Java's equals(Object) method?

Answer:
Update (March 2022):
A proposal is underway to introduce Records and Tuples, which are immutable structures that enable direct comparison by value instead of reference. This would extend to Set and Map objects, allowing for key comparisons/lookups based on object content.

Original Answer:
The ES6 Set object lacks customizable comparison methods. It is not possible to extend its .has(), .add(), and .delete() methods to perform deep object comparisons.

Attempting to derive a custom object from Set and override the aforementioned methods with deep comparison logic would result in poor performance due to the lack of support from the underlying Set object, requiring brute force iteration to locate matches.

As noted in the ES6 specification, the feature to configure equality comparison in Sets has been postponed due to implementation challenges. It is recommended to compare primitive values or immutable value objects for equality in Sets, as they are compared by value by default in JavaScript.

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