Ahead of any validation for forms should be input masks at every reasonable step.
Make sure that only numbers can be entered into a phone field, and with the correct pattern. Ensure that postal codes can only have numbers and letters, and the letters come in uppercase even if the user presses a lowercase letter. Have a date picker available, sure, but give people the option of just typing it out, and also make it clear that the format will be ISO-8601.
Well thought out input masks provide proactive correction and can massively help avoid reactive validation that only comes up after the user leaves the field or submits the form.
Ahead of any validation for forms should be input masks at every reasonable step.
Make sure that only numbers can be entered into a phone field, and with the correct pattern. Ensure that postal codes can only have numbers and letters, and the letters come in uppercase even if the user presses a lowercase letter. Have a date picker available, sure, but give people the option of just typing it out, and also make it clear that the format will be ISO-8601.
Well thought out input masks provide proactive correction and can massively help avoid reactive validation that only comes up after the user leaves the field or submits the form.