Safari / Firefox triggering OPTIONS calls

[dapope]

Front-end app - the feed doesn't work for us in Safari and Firefox. It appears that setting the userAgent in the code causes those browsers to do an OPTIONS request. (In our case, the options request fails because of CORS and we don't have access to the source application)

Would be nice if setting the user agent was an optional setting.
'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:45.0) Gecko/20100101 Firefox/45.0',

Thx-