[ES6] ITERATORS

Iterables return an iterator object. This object knows how to access items from a collection 1 at a time, while keeping track of its current position within the sequence.

 

let user = {
  name: "sam", totalReplies: 17, isBlocked: false
};

user[Symbol.iterator] = function(){

  let properties = Object.keys(this);
  let count = 0;
  let isDone = false;

  let next = () => {
    if(count >= properties.length){
      isDone = true;
    }

    let value = this[properties[count++]];

    return {done: isDone, value} ;
  };
  return { next };
};