Get the list of methods in a constructor in javascript

Question

I Want to parse a class to get a list of all the members declared in this class. So:

given:

class MyClass {
    someMethod(){
        console.log('someMethod');
    }
    someOtherMethod(){}
}
/// this does not work
function Debuggable(constructor: Function) {
    console.warn('Debuggable called', constructor)

    for (let prop in constructor.prototype) {
        console.warn('prop', prop);    
    }

    console.warn('key', Object.keys(constructor.prototype));    

}

I need to be able to call Debuggable(MyClass) and get an array with ['someMethod','someOtherMethod' ].

Is this possible?

As final goal I want to create a typescript decorator that calls a function before call a method inside an instance of that class.