[ES6] The Iterator Protocol

const digits = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
const arrayIterator = digits[Symbol.iterator]();

console.log(arrayIterator.next());
console.log(arrayIterator.next());
console.log(arrayIterator.next());

/*
Object {value: 0, done: false}
Object {value: 1, done: false}
Object {value: 2, done: false}
*/

/*
 * Programming Quiz: Make An Iterable Object
 *
 * Turn the `james` object into an iterable object.
 *
 * Each call to iterator.next should log out an object with the following info:
 *   - key: the key from the `james` object
 *   - value: the value of the key from the `james` object
 *   - done: true or false if there are more keys/values
 *
 * For clarification, look at the example console.logs at the bottom of the code.
 *
 * Hints:
 *   - Use `Object.keys()` to store the object‘s properties in an array.
 *   - Each call to `iterator.next()` should use this array to know which property to return.
 *   - You can access the original object using `this`.
 *   - To access the values of the original object, use `this` and the key from the `Object.keys()` array.
 */

const james = {
    name: ‘James‘,
    height: `5‘10"`,
    weight: 185
};

james[Symbol.iterator] = function() {
    var keys = Object.keys(james);
    var nextIndex = 0;
    return {
        next: function() {
            var key = keys[nextIndex];
            var obj = {
                key: key,
                value: james[key],
                done: nextIndex === keys.length-1 ?
                        true:
                        false
            };
            nextIndex++;
            return obj;
        }
    }
}


 const iterator = james[Symbol.iterator]();
//
 console.log(iterator.next().value); // ‘James‘
 console.log(iterator.next().value); // `5‘10`/ 
 console.log(iterator.next().value); // 185