class.js

const skillSet = context => {
  return {
    nameSkills: {
      getName() {
        return context.name;
      },
      setName(name) {
        context.name = name;
      }
    }
  };
};

class SecretSkills {
  constructor(context) {
    this.context = context;
  }

  get nameSkills() {
    const self = this;
    return {
      getName() {
        return self.context.name;
      },
      setName(name) {
        self.context.name = name;
      }
    };
  }
}

class People {
  constructor(name) {
    this.name = name;
    this.skills = skillSet(this);
    this.secretSkills = new SecretSkills(this);
  }
}

const people = new People("World");
console.log(people.skills.nameSkills.getName());

const people2 = new People("Hello");
console.log(people2.secretSkills.nameSkills.getName());

class_es5.js

var skillSet = (function (context) {
    return {
        nameSkills: {
            getName: function () {
                return context.name;
            },
            setName: function (name) {
                context.name = name;
            }
        }
    };
});
var SecretSkills = /** @class */ (function () {
    function SecretSkills(context) {
        this.context = context;
    }
    Object.defineProperty(SecretSkills.prototype, "nameSkills", {
        get: function () {
            var self = this;
            return {
                getName: function () {
                    return self.context.name;
                },
                setName: function (name) {
                    self.context.name = name;
                }
            };
        },
        enumerable: true,
        configurable: true
    });
    return SecretSkills;
}());
var People = /** @class */ (function () {
    function People(name) {
        this.name = name;
        this.skills = skillSet(this);
        this.secretSkills = new SecretSkills(this);
    }
    return People;
}());
var people = new People('World');
console.log(people.skills.nameSkills.getName());
var people2 = new People('Hello');
console.log(people2.secretSkills.nameSkills.getName());