Checking whether something is iterable

Question

In the MDN docs: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of

The for...of construct is described to be able to

Answer 1

The simplest solution is actually this:

function isIterable (value) {
  return Symbol.iterator in Object(value);
}

Object will wrap anything which isn't an object in one, allowing the in operator to work even if the original value is not an Object. null and undefined are turned into empty objects so there's no need for edge case detection, and strings get wrapped into String objects which are iterable.