When populating the date in the input field (not via the datepicker itself) date is treated as US format. For example, after typing in input field - 10/01/2019 it becomes 01/10/2019 and when opening the date picker the date is first of October 2019.
when selecting the date via the date picker there is no issue and selected date is displayed as dd/MM/yyyy
UPDATE There was a "bug" in format function -need a parenthesis in ('0'+(date.getMonth()+1)).slice(-2)-
just create a DateAdapter
Then use as provider
see in
stackblitz
If you are using the angular material datepicker you can overide the locale wich is US by default. see this link : https://material.angular.io/components/datepicker/overview#internationalization
You need to set the useValue to fr-FR or other locale that uses the dd/MM/yyyy