javascript里面获取当前时间以及与当前时间相差天数的时间

//获取当前时间

function getNowFormatDate() {

    var date = new Date();

    return getFormatDate(date);
}

//获得之前时间，传入参数为相差的天数，如果需要向后的时间，减号改为加好

function getBeforeFormatDate(num){
var date = new Date();
date = date.valueOf() - num*24*60*60*1000;
date = new Date(date);
return getFormatDate(date);

}

//格式化时间

function getFormatDate(date){

    var seperator1 = "-";

    var seperator2 = ":";

    var month = date.getMonth() + 1;

    if (month >= 1 && month <= 9) {

        month = "0" + month;

    }

    //如果位数不足两位，补0

    var strDate =   addstrzero(date.getDate());

    var strHour =   addstrzero(date.getHours());

    var strmin =    addstrzero(date.getMinutes());

    var strseconds =addstrzero(date.getSeconds());

    var currentdate = date.getFullYear() + seperator1 + month + seperator1 + strDate

            + " " + strHour + seperator2 + strmin + seperator2 + strseconds;

    return currentdate;

}

//如果位数不足两位，补0

function addstrzero(num){
if(num >= 0 && num <= 9){
num = "0"+num;
}
return num;

}