DOM iterables on top of es6-symbol polyfill

es6-symbol-iterators.js

function iterator() {
  const self = this
  let i = 0
  return {
    next: function() {
      return {
        done: i === self.length,
        value: self[i++]
      }
    }
  }
}

if (!Array.prototype[Symbol.iterator]) {
  Array.prototype[Symbol.iterator] = iterator
}

if (!NodeList.prototype[Symbol.iterator]) {
  // IE11 refuses to assign directly onto NodeList.prototype
  Object.defineProperty(NodeList.prototype, Symbol.iterator, {
    enumerable: false,
    configurable: true,
    get: function() { return iterator }
  })
}

if (!HTMLCollection.prototype[Symbol.iterator]) {
  // IE11 refuses to assign directly onto HTMLCollection.prototype
  Object.defineProperty(HTMLCollection.prototype, Symbol.iterator, {
    enumerable: false,
    configurable: true,
    get: function() { return iterator }
  })
}

if (window.Headers && !Headers.prototype[Symbol.iterator]) {
  Headers.prototype[Symbol.iterator] = function() {
    const items = []
    this.forEach(function(value, name) {
      items.push([name, value])
    })
    return items[Symbol.iterator]()
  }
}