You can parse the date using the Date
constructor, then spit out the individual time components:
function convert(str) {_x000D_
var date = new Date(str),_x000D_
mnth = ("0" + (date.getMonth() + 1)).slice(-2),_x000D_
day = ("0" + date.getDate()).slice(-2);_x000D_
return [date.getFullYear(), mnth, day].join("-");_x000D_
}_x000D_
_x000D_
console.log(convert("Thu Jun 09 2011 00:00:00 GMT+0530 (India Standard Time)"))_x000D_
//-> "2011-06-08"
_x000D_
As you can see from the result though, this will parse the date into the local time zone. If you want to keep the date based on the original time zone, the easiest approach is to split the string and extract the parts you need:
function convert(str) {_x000D_
var mnths = {_x000D_
Jan: "01",_x000D_
Feb: "02",_x000D_
Mar: "03",_x000D_
Apr: "04",_x000D_
May: "05",_x000D_
Jun: "06",_x000D_
Jul: "07",_x000D_
Aug: "08",_x000D_
Sep: "09",_x000D_
Oct: "10",_x000D_
Nov: "11",_x000D_
Dec: "12"_x000D_
},_x000D_
date = str.split(" ");_x000D_
_x000D_
return [date[3], mnths[date[1]], date[2]].join("-");_x000D_
}_x000D_
_x000D_
console.log(convert("Thu Jun 09 2011 00:00:00 GMT+0530 (India Standard Time)"))_x000D_
//-> "2011-06-09"
_x000D_