How Can I Achieve Deep Equality Comparison for Elements in a JavaScript Set Object?

Customizing Equality for JavaScript Set Objects

In ES6 (Harmony), the new Set object introduces reference equality for its elements. However, this behavior may not always be suitable for comparing objects deeply.

Unintended Behavior for Object Equality:

Consider the following code snippet:

var set = new Set();
set.add({a:1});
set.add({a:1});
console.log([...set.values()]); // Array [ Object, Object ]

As you can see, even though both objects have the same properties and values, they are considered distinct due to reference equality.

Custom Comparison for Set Objects:

Unfortunately, the ES6 Set object does not provide built-in methods for customizing equality comparisons. Extending it to override the comparison logic would also be challenging.

Potential Workaround:

Although custom comparison for Set objects is not directly supported, you can consider using an alternative data structure or technique:

1. Immutable Value Objects:

The article mentioned in the response suggests using immutable value objects, which would allow the Set to use deep value comparison. However, this is not currently a standard in JavaScript.

2. Custom Data Structure with Deep Comparison:

You could create your own custom data structure that inherits from Set and overrides the methods that use object identity. However, this would require a complete rewrite of the Set implementation, which would not be efficient for large sets.

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