Jquery calendar

I have a textbox that use for my calendar

$("#txtDueBackDate").datepicker({
            formatDate: data.formatDueBackDate,
        });

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When user initiates the page the textbox filled up with a date like 7\12\2017.
Now when I click on the calendar I would like to highlight two dates
1. the date of today.
2. the date which show at the textbox.

Please, Help.

Thanks,