I want to format Date YYYYY-MM-DD, but getFullYear does not exist.

Uncaught TypeError:date.getFullYear is not a function
    at formatDate
happens

function formatDate(date){

        varmonth=("0"+(date.getMonth()+1)).slice(-2);
        vardate=("0" + date.getDate()) .slice(-2);

        varformatted=`${date.getFullYear()}-${month}-${date}`.replace(/\n|\r/g, ');
        return formatted;
    }