Weekday

by Mentaldiarrhoe

HTML

<html>
<body>

<span id="x">05.09.2021</span><br>
<span id="out">test</span>
</body>
</html>

JavaScript

function day() {
var regex=/([0-9]{2})\.([0-9]{2})\.(\d{4})\?/;
if (regex.test(x.innerText)) {
var fx=x.innerText.replace(regex,"$3/$2/$1");
var day = new Date(fx);
var week = new Array(
    "Sunday",
    "Monday",
    "Tuesday",
    "Wednesday",
    "Thursday",
    "Friday",
    "Saturday"
);

for (i=0; i<week.length; i++) {
     var num = (day.getDay(i));
     //out.innerHtML(week[num])
    out.innerText=fx;//week[num];
   
   
}

/*
function ISO8601_week_no(dt)  {
     var tdt = new Date(dt.valueOf());
     var dayn = (dt.getDay() + 6) % 7;
     tdt.setDate(tdt.getDate() - dayn + 3);
     var firstThursday = tdt.valueOf();
     tdt.setMonth(0, 1);
     if (tdt.getDay() !== 4) 
       {
      tdt.setMonth(0, 1 + ((4 - tdt.getDay()) + 7) % 7);
        }
     return 1 + Math.ceil((firstThursday - tdt) / 604800000);
        }

dt = new Date(fx);
//out.innerText=out.innerText +"/ Woche " +ISO8601_week_no(dt);

}
}
day();
/*