iterators.js

/**
 * Custom Iterator
 * Making an Object iterable by using for...of loop
 * By Muhammad Lahin
 */

let obj = {
  id: 1,
  name: "John Cena",
  profession: "Wrestling"
}

obj[Symbol.iterator] = function () {
  let counter = -1;
  return {
    next: function () {
      counter++;
      switch (counter) {
        case 0: 
          return { value: obj.id, done: false }
        case 1: 
          return { value: obj.name, done: false }
        case 2: 
          return { value: obj.profession, done: false }
        default: 
          return { done: true }
      }
    }
  }
}

for (let val of obj) {
  console.log(val) // 1, John Cena, Wrestling
}