why `PUT` verb automati convert to 'OPTIONS' verb?

[shikelong]

Here is how i use isomorphic-fetch in my function. But In the chrome dev tools. the http request method is OPTIONS.

export const putGroup = (data) => {
  return (dispatch) => {
    dispatch(updateGroup());
    return fetch(GROUP_ADDR, {
      method: 'PUT',
      body: JSON.stringify(data)
    })
    .then((response) => {
      if (response.ok){
        return response.json();
      }
      return {status: response.status, statusText: response.statusText};
    })
    .then((data) => {
      dispatch(updateGroupSuccess(data));
    }, (error) => {
      dispatch(updateGroupFailure(error));
    });
  };
}

Regards.