New section CORS in Web Apps was added to Taking advantage of Web Apps with Google Apps Script
In this section, I would like to introduce CORS in Web Apps. As the result, in order to prevent the error related to CORS, it was found the following important points.
It is required to return
For POST method, the data is required to be converted to the string and sent to Web Apps.
You can see the detail of this section using the sample scripts at https://github.com/tanaikech/taking-advantage-of-Web-Apps-with-google-apps-script#corsinwebapps