iterables-code-05.js

const data = {
 items: ["A", "B", "C"],
 pointerIndex: 0,
 next() {
   if (this.pointerIndex < this.items.length) // if done
     return { value: this.items[this.pointerIndex++], done: false }
   else // if not done
     return { value: undefined, done: true };
 }
}

for(let item of data) {
   console.log(item);
}

//o: Uncaught TypeError: data is not iterable