Iterable : Object

<p>
An iterable object is any object that has a
%%/Symbol#iterator|**Symbol.iterator**%% property whose value is a 
function that returns an %%/Iterator|**Iterator**%%.
</p>

<p>
You can loop over all values in an iterable object by using a 
**for (const value of iterable) { }** loop.
</p>

<p>
You may create your own iterable object by assigning the
%%/Symbol#iterator|**Symbol.iterator**%% property to a
generator function (**function* () {}**) or an object with a 
%%/Iterator#next|**next()**%% method.
</p>

<p>
See %%/Iterator|Iterator%% for more details.
</p>

Version:
ECMAScript 2015

Spec:
http://www.ecma-international.org/ecma-262/6.0/#sec-iterable-interface

----
instance[Symbol.iterator] : Function<Iterator>

Returns a function that produces an Iterator for this object.

<example>
// Arrays are a built in Iterable object
const arr = ['a', 'b', 'c'];

// Use for (... of ...) loop to get the values of an iterable
for (const x of arr) {
  console.log(x);
} 

// Create an iterable class with a generator function
class MyIterable {
  constructor(maxValue) {
    this._maxValue = maxValue;
  }

  *[Symbol.iterator]() {
    for (let i = 0; i < this._maxValue; i++) {
      yield i;
    }
  }
}

for (const x of new MyIterable(3)) {
  console.log(x);
}

// Under the covers, for (... of ...) does the following: 
const iterator = arr[Symbol.iterator]();
let current = iterator.next();
while (!current.done) {
  console.log(current.value);
  current = iterator.next();
}
</example>