how a counter generator in es6 maps to a function in es5

counter-generator.js

function* counter() {
  var count = 0;
  while (true) {
    yield count++;
  }
}

counter-normal.js

function counter() {
  var done = false;
  var count = 0;
  return {
    next: function (value) {
      if (done) throw new Error('Generator is done');
      return {done: done, value: count++};
    },
    throw: function (err) {
      done = true;
      throw err;
    }
  }
}