ES 2015 iterator sample based on http://learn.javascript.ru/iterator

es2015-iterator-sample.js

(function () {
  'use strict';

  let range = {
    from: 1,
    to: 5
  }

  // make object range iterable
  range[Symbol.iterator] = function() {

    let current = this.from;
    let last = this.to;

    // method must return object with next()
    return {
      next() {
        if (current <= last) {
          return {
            done: false,
            value: current++
          };
        } else {
          return {
            done: true
          };
        }
      }

    }
  };

  for (let num of range) {
    console.log(num); // 1, 2, 3, 4, 5
  }
})();