Function getIteratorFn

docs/external/js/react-dom.development.js:1425–1437

(maybeIterable)

  var MAYBE_ITERATOR_SYMBOL = typeof Symbol === 'function' && Symbol.iterator;
  var FAUX_ITERATOR_SYMBOL = '@@iterator';
  function getIteratorFn(maybeIterable) {
    if (maybeIterable === null || typeof maybeIterable !== 'object') {
      return null;
    }

    var maybeIterator = MAYBE_ITERATOR_SYMBOL && maybeIterable[MAYBE_ITERATOR_SYMBOL] || maybeIterable[FAUX_ITERATOR_SYMBOL];

    if (typeof maybeIterator === 'function') {
      return maybeIterator;
    }

    return null;
  }

  var Uninitialized = -1;
  var Pending = 0;