My preferred javascript timestamp - an implementation of an ISO 8601 wannabe

preferred_timestamp.js

function Timestamp () {
    var d, t, year, month, day, hour, minute, second, millisecond;
 
    d = new Date();
     
    t = '';
     
    year = d.getFullYear();
    month = ('00' + (Number(d.getMonth()) + 1)).slice(-2);
    day = ('00' + d.getDate()).slice(-2);
    hour = ('00' + d.getHours()).slice(-2);
    minute = ('00' + d.getMinutes()).slice(-2);
    second = ('00' + d.getSeconds()).slice(-2);
    millisecond = ('0000' + d.getMilliseconds()).slice(-4);
     
    t = year + month + day + hour + minute + second + millisecond;
    
    this.t = t;
};

Timestamp.prototype.toString = function () {
    return this.t;
};