JavaScript Time Functions

<script>

    function linebreak (){
        document.write("<br>");
    } ;

    function horizontalRule(){
        document.write("<hr>");
    };

    newdateobject = new Date();
    dd = newdateobject.getDate();
    mm = newdateobject.getMonth()+1;
    yyyy = newdateobject.getFullYear();
    h = newdateobject.getHours();
    m = newdateobject.getMinutes();
    s = newdateobject.getSeconds();
    d = newdateobject.getDay();
    weekday = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday'];


    if(dd<10){
        dd = '0' + dd
    }
    if(mm<10){
        mm='0' + mm
    }

    if(h<10){
        h='0' + h
    }

    if(m<10){
        m='0' + m
    }

    if(s<10){
        s ='0' + s
    }


    //today =   mm + '/' + dd + '/' + yyyy + ' ' + weekday[d] + ' ' +  h + ':' + m +':' + s;

    today =   mm + '-' + dd + '-' + yyyy + ' ' + weekday[d] 

    document.getElementById("topright").innerHTML = today;
    

    setInterval(function(){
        timerobject=new Date();
        document.getElementById("topcenter").innerHTML = timerobject.toLocaleTimeString();
    },10);


    dateobject =    new Date();


    //----Date()-------------------------------------
    document.write("Date() --  ");
    linebreak();
    document.write(dateobject);
    horizontalRule();
    linebreak();

    //-----Date() + toString()------------------------------------
    document.write("Date() toString() [same as Date()]--");
    linebreak();
    document.write(dateobject.toString());
    horizontalRule();
    linebreak();

    //-----Date() + toLocaleString()------------------------------------
    document.write("Date() toLocaleString() -- ");
    linebreak();
    document.write(dateobject.toLocaleString());
    horizontalRule();


    //-----TIME SINCE 1970------------------------------------
    document.write("<h4>Time Since 1970</h4>");
    newTimeMilliseconds = dateobject.getTime();
    document.write("milliseconds since 1/1/1970: ");
    document.write(newTimeMilliseconds);
    linebreak();

    newTimeSeconds = newTimeMilliseconds / 1000;
    document.write("seconds since 1/1/1970: ");
    document.write(newTimeSeconds.toFixed(2));
    linebreak();

    newTimeMinutes = newTimeSeconds / 60;
    document.write("minutes since 1/1/1970: ");
    document.write(newTimeMinutes.toFixed(2));
    linebreak();

    newTimeHours = newTimeMinutes / 60;
    document.write("hours since 1/1/1970: ");
    document.write(newTimeHours.toFixed(2));
    linebreak();

    newTimeDays = newTimeHours / 24;
    document.write("days since 1/1/1970: ");
    document.write(newTimeDays.toFixed(2));
    linebreak();

    newTimeYears = newTimeDays / 365;
    document.write("years since 1/1/1970: ");
    document.write(newTimeYears.toFixed(2));
    horizontalRule();



//-------TIME SINCE DOB-------------------------------------

var birthdate = new Date(1984, 0, 1);
var currentdate = dateobject;

document.write("<h4>Time Since DOB </h4>");


document.write("current day: " + currentdate);
linebreak();
refnow = dateobject.getTime();
document.write("milliseconds since 1/1/1970: ");
document.write(refnow);
linebreak();
linebreak();

document.write("birthday: " + birthdate);
linebreak();
refbirth = birthdate.getTime();
document.write("milliseconds since birthday:");
document.write(refbirth);
linebreak();
linebreak();



document.write("difference in milliseconds (time passed) between today and birthday: ");
differenceMilliseconds = refnow - refbirth;
document.write(differenceMilliseconds);
linebreak();
linebreak();

document.write("milliseconds since birth: ");
document.write(differenceMilliseconds);
linebreak();

differenceSeconds = differenceMilliseconds / 1000;
document.write("seconds since birth: ");
document.write(differenceSeconds.toFixed(2));
linebreak();

differenceMinutes = differenceSeconds / 60;
document.write("minutes since birth: ");
document.write(differenceMinutes.toFixed(2));
linebreak();

differenceHours = differenceMinutes / 60;
document.write("hours since birth: ");
document.write(differenceHours.toFixed(2));
linebreak();

differenceDays = differenceHours / 24;
document.write("days since birth: ");
document.write(differenceDays.toFixed(2));
linebreak();

differenceYears = differenceDays / 365;
document.write("years since birth: ");
linebreak();
document.write(differenceYears.toFixed(2)+ "<br>");
horizontalRule();


</script>