I'm creating a website for doctor appointments, and in the form the user can select the date when he wants to go to the appointment. The problem is that the input type 'date' lets the user select past date, and still submit the form.
I want to not let the user be able to select past date, and being able to only select today date or future date (tomorrow or another date of the month).
How can I achieve that without plugins (datepicker and others)?