I found reference #1 (below) of how to set defaults for a date field picker. For some reason you have to set the default of beforeShow to a function which then sets the option of beforeShowDay.

Not sure what the redundancy is here, but it does work.

So I came up with this code:

  function checkField(input) {
   
     $(input).datepicker("option", {beforeShowDay: function(d){ 
            
      var ds = d.toDateString();
      
      return [ds==getPreviousMonday() || ds==getFutureMondayOf(1) || ds==getFutureMondayOf(2) || ds==getFutureMondayOf(3) || ds==getFutureMondayOf(4) ,""];}
   });
    
  }
  
  $.datepicker.setDefaults({beforeShow: checkField});

It works! The problem with this code is that $.datepicker is not class dependent, which means it will seek out and apply to any date field it finds. That is not going to work in many cases. So I found reference #2 (below) where it was stated you need to use an option instead of setDefaults if you want to work by class name.

So this is odd, now I am switching back to the option method to call the beforeShow so I can call the beforeShowDay

I switched the last line of my code to this:

 $('.myDateField').datepicker("option", {beforeShow: checkField});

Nothing happens.

I tried just setting my beforeShowDay this way as well instead of creating a function called checkField, but nothing happens there either.

I exclusively use classes to make sure I am working with the right field(s). How would I set defaults on a date by class name?

Reference #1 https://answers.laserfiche.com/questions/173587/Restricting-Date-Picker#174123

Reference #2 https://answers.laserfiche.com/questions/182596/Forms-Calendar--Restrict-to-specific-list-of-dates#182648