Fat Arrows and This Scope.js

// This does not loose scope with fat arrow
var bob = {
  _name: "Bob",
  _friends: ["Jon", "Daenerys", "Arya", "Tyrion"],
  printFriends() {
    this._friends.forEach(f => // this === bob
      console.log(this._name + " knows " + f)); // this === bob ("I should be undefined but I am bob")
  }
}
/*
Output: 
Bob knows Jon
Bob knows Daenerys
Bob knows Arya
Bob knows Tyrion
*/

var bob = {
  _name: "Bob",
  _friends: ["Jon", "Daenerys", "Arya", "Tyrion"],
  printFriends() {
    this._friends.forEach(function(f){ // this === bob
      console.log(this._name + " knows " + f); // this === bob ("I knew you wouldn't believe me")
    })
  }
}
/*
Output: 
undefined knows Jon
undefined knows Daenerys
undefined knows Arya
undefined knows Tyrion
*/
bob.printFriends()