JS將指定的時間戳轉為UTC時間

　　Js中獲取時間戳可用var dayMiliseconds = parseInt(new Date().valueOf());Js的時間戳單位為毫秒（1s = 1000 ms）,下面是一個將制定的格式轉化成UTC時間的函數。

//format the date string from webservice to UTC time;
function toUTCtime(dateStr) {
    //Date(1381243615503+0530),1381243615503,(1381243615503+0800)
     
    dateStr += "";
    var utcPrefix = 0;
    var offset = 0;
    var dateFormatString = "yyyy-MM-dd hh:mm:ss";
    var utcTimeString = "";
    var totalMiliseconds = 0;

    var regMatchNums = /\d+/gi;
    var regSign = /[\+|\-]/gi;
    var arrNums = dateStr.match(regMatchNums);
    utcPrefix = parseInt(arrNums[0]);
    if (arrNums.length > 1) {
        offset = arrNums[1];
        offsetHour = offset.substring(0, 2);
        offsetMin = offset.substring(2, 4);
        offset = parseInt(offsetHour) * 60 * 60 * 1000 + parseInt(offsetMin) * 60 * 1000;
    }
    if(dateStr.lastIndexOf("+")>-1){
        totalMiliseconds= utcPrefix - offset;
    } else if (dateStr.lastIndexOf("-") > -1) {
        totalMiliseconds = utcPrefix + offset;
    }

    utcTimeString = new Date(totalMiliseconds).format(dateFormatString);
    return utcTimeString;

   
}