ES6 - for loops

for-loops.js

// ES6 for loops
// =============

// Things in ES6 can be "iterable". Arrays are iterable by default.

var fruits = ['Apple', 'Banana', 'Grape'];

for (var fruit of fruits)
  console.log('Fruit: ' + fruit);

// => "Fruit: Apple"
// => "Fruit: Banana"
// => "Fruit: Grape"

// Objects apparently not iterable as anyone in the planet would expect.
// You need to declare an iterator which is a method that defines how
// each property is return.
// Y U NO USE A DEFAULT ITERATOR?!

var person = { name: 'Joe', age: 25, bio: 'Long bio here' };

var attributes = function(person) {
  for (var attr in person) yield [attr, person[attr] ]
};

for (var [attribute, value] of attributes(person))
  console.log(attribute + ': ' + value);

You should avoid unguarded for/in loops on objects. You have to check for object.hasOwnProperty()

I believe you also forgot the asterisk in the attributes generator function