Overriding ES6 class behaviour with traps - node.js

Question

I have recently learned about Proxy objects in javascript, and how you can use a Proxy object to hook into Object.defineProperty for custom behaviour (see this answer if I'm being too vague).
I would like to do the same, but to an entire class so that I can achieve something similar to C#'s INotifyPropertyChanged interface. Essentially, the class will be an EventEmitter that emits data when a property is changed.
class SyncedObject extends EventEmitter {
constructor() {
this.ValueA = 1;
this.ValueB = 2;
}
// Emit this when a property is changed
emitPropertyChanged( eventArgs ) {
// eventArgs.propertyName
// eventArgs.oldValue
// eventArgs.newValue
this.emit( 'propertyChanged', eventArgs );
}
}
Is this something I can do in an ES6 class? I understand Proxy has a get() and set() traps that could achieve this kind of thing, but I'm not sure how to go about writing a class that is automatically wrapped in a Proxy.

Answer 1

After some tinkering, I've been able to more or less achieve what I was hoping to
const EventEmitter = require( 'events' );
class SyncedObject extends EventEmitter {
constructor( obj ) {
super();
this._object = obj;
return new Proxy( this, {
set: ( object, key, value, proxy ) => {
if( this._object[key] === value )
return false;
this._object[key] = value;
if( key[0] === '_') {
var eventArgs = {
propertyName: key,
oldValue: object[key],
newValue: value
};
this.emit( 'propertyChanged', eventArgs );
}
return true;
},
get: ( object, key ) => {
return this._object[key] || object[key];
}
});
}
silentUpdate( data ) {
for(var i = 0, keys = Object.keys(data); i < keys.length; i++)
this._object[keys[i]] = data[keys[i]];
}
}
Not the most bulletproof solution (EventEmitter properties raise the event), but for what I need, it will likely do. If anyone has improvement suggestions, please do post. I'll leave this question open for the time being.