User is free to enter any thing in datepicker text box.

[rakeshy3]

User is free to enter any thing in datepicker text box. it should only allow to enter date in chosen format and date only not any text. Please suggest how I can achieve this.

[barlowm]

I've seen that as well (on MOST of the date pickers that use a text field.)
I added my own handler to trap that:

$('#date').keydown(function(e) {
	const validKeys = /[0-9\.\-\/]/;
	 if((e.key.match(validKeys))) {
		return true;
	 }
	 else {
	 	return false;
	 }
})

This allows only numbers and "-" or "/" or "." as separators (so you can enter dates as "01/01/2001" or "01-02-2002" or "01.03.2003")
It doesn't trap for all possible errors (like entering "/1.2-3") but that can be done as well. I just validate (using moment) on blur of the field.

Now granted that type of input validation could (and really should) be done as part of the module. I just don't have the time to make a PR for it at the moment.

Hope that helps