Show day-of-week in panel date field

How can I show the day-of-the-week name (e.g. Friday) on screen?
when the user is editing a date in the panel

I want to give the user a reference which day of the week a certain date represents - for usability.

I thought:
Maybe show the day-of-the-week in an extra field or in the same date field.
But I didn’t succeed in showing this in the panel. I tried changing the display attribute of the date field in the blueprint:
display: DAY D-M-Y and I tried display: dddd D-M-Y

and I tried several things to add a calculated or computed field. But that didn’t work at all as you can see in my blueprint example. I didn’t even succeed in displaying a fixed value let alone a calculated day-of-week:

        label: First Day
        type: date
        display: D-MM-YY
        width: 1/4
        label: '{eerstedag}'
        type: text
        value: 'Vrijdag' 

Is it possible to display a day-of-the-week (example: ‘Friday’) during editing in the panel?
How can I achieve it?


Showing the name of the day is not supported, it seems, see Date | Kirby CMS

You could display the date with the before option:

before: "{{'l') }}"

But that will only update after saving and reloading.

Thank you for the answer and the correct syntax of the ‘before:’ attribute.