script.js

//finding today's date
function calendar(){
    var day=['Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday'];
    var month=['January','February','March','April','May','June','July','August','September','October','November','December'];
    var d=new Date();  //to get current date
    setText('calendar-day', day[d.getDay()]);
    setText('calendar-date', d.getDate());
    setText('calendar-month-year', month[d.getMonth()]+' '+(1900+d.getYear()));
};

function setText(id, val){
    if(val < 10){
        val = '0' + val;    //add leading 0 if date < 10
    }
    document.getElementById(id).innerHTML = val;
};

//call calendar() when page load
window.onload = calendar;