I\'ve been working on an answer to StackOverflow question Datepicker: Disabling dates in the data. I\'ve successfully developed a small webapp that excludes specific dates from
You can get values from the Apps Script runtime with client-side code.
To do this you need to handle the response from the function you calling with the withSuccessHandler function.
Changing your function to create the DatePicker with the date returned from the backend would look like this: