Please try using prototype method as following.
Date.prototype.YYYYMMDDHHMMSS = function () {
var yyyy = this.getFullYear().toString();
var MM = pad(this.getMonth() + 1,2);
var dd = pad(this.getDate(), 2);
var hh = pad(this.getHours(), 2);
var mm = pad(this.getMinutes(), 2)
var ss = pad(this.getSeconds(), 2)
return yyyy + MM + dd+ hh + mm + ss;
};
function getDate() {
d = new Date();
alert(d.YYYYMMDDHHMMSS());
}
function pad(number, length) {
var str = '' + number;
while (str.length < length) {
str = '0' + str;
}
return str;
}