On Tue, Dec 15, 2015 at 2:37 PM, Thomas Steiner tomac@google.com wrote:
On a more technical note—trying to be a good citizen [3]—the client library sets an identifying User-Agent header in Node.js mode. However, trying to set the corresponding X-User-Agent (note the "X-") header from a browser context (XMLHttpRequest cannot override the browser's intrinsic User-Agent for security reasons), this fails with an error message "Request header field X-User-Agent is not allowed by Access-Control-Allow-Headers in preflight response". Maybe you could change your CORS settings and include X-User-Agent in your Access-Control-Allow-Headers?!