Change dates in javascript

navigateDate.js

var date = new Date();
                        date.setDate(date.getDate() - k);

                        var dateMsg = date.getFullYear() + "-" + zeroFill(date.getMonth() + 1, 2) + "-" + zeroFill(date.getDate(), 2);

function zeroFill(number, width) {
width -= number.toString().length;
if (width > 0) {
return new Array(width + (/./.test(number) ? 2 : 1)).join('0') + number;
}
return number + ""; // always return a string
}