JS日期格式转换

Fri Oct 31 18:00:00 UTC+0800 2008

转为   

2008-10-31

function Todate(num) { //Fri Oct 31 18:00:00 UTC+0800 2008
            num = num + "";
            var date = "";
            var month = new Array();
            month["Jan"] = 1; month["Feb"] = 2; month["Mar"] = 3; month["Apr"] = 4; month["May"] = 5; month["Jun"] = 6;
            month["Jul"] = 7; month["Aug"] = 8; month["Sep"] = 9; month["Oct"] = 10; month["Nov"] = 11; month["Dec"] = 12;
            var week = new Array();
            week["Mon"] = "一"; week["Tue"] = "二"; week["Wed"] = "三"; week["Thu"] = "四"; week["Fri"] = "五"; week["Sat"] = "六"; week["Sun"] = "日";
            str = num.split(" ");
            date = str[5] + "-";
            date = date + month[str[1]] + "-" + str[2];
            return date;
}