1th of 38 Questions.
What built-in JavaScript data structures are iterable by default? How does for...of work under the hood with them?
Array, String, Map, Set, TypedArray, arguments, and NodeList are iterable by default. for...of calls the [Symbol.iterator]() method and loops over the value property of each next() result until done is true.
Under the hood, for...of obtains the iterator by calling the object's [Symbol.iterator]() method, then repeatedly calls the iterator's next() method, storing the value property in the loop variable and stopping when done is true. Example: const arr = [1,2,3]; for (const v of arr) { console.log(v); }