Using DatePicker On Webpage Input Form?

I would like to use a date picker on a web page input form. I found one which does what I want but the date format it outputs is not correct for my form. The script contains the following:

// datetime parsing and formatting routimes. modify them if you wish other
datetime format
function str2dt (str_datetime) {
var re_date = /^(d+)-(d+)-(d+)s+(d+):(d+):(d+)$/;
if (!re_date.exec(str_datetime))
return alert("Invalid Datetime format: "+ str_datetime);
return (new Date (RegExp.$3, RegExp.$2-1, RegExp.$1, RegExp.$4,
[Code] .....

I am not familiar with JavaScript and have not been able to figure out what changes I need to make in order to get the output I want. I tried to contact the author, but his email address no longer works. What modifications are necessary. The output format I'm looking for is YYYY-MM-DD (no time).