i'm tring to put together standard html5 form validation (using required attribute and a submit button) in forms with "file" input fields using the HTML service apps script.
My problem is passing blob files to the apps script function using a submit button. If i put a normal button i lose the standard validation of the html5. If i use a submit button nothing is passed to the apps script function with the "google.script.run" statement.
The example of the tutorial use a normal button, but in this way i cannot use form validation for required fields.
How i can handle this? Since now i had to use a submit button and the onclick event, and checked manually if required fields were inserted (in the apps script function called by the button).