js获取当前日期、前一天、后一天的日期的例子

<script>
function addByTransDate(dateParameter, num) {
    var translateDate = "", dateString = "", monthString = "", dayString = "";
    translateDate = dateParameter.replace("-", "/").replace("-", "/");
    var newDate = new Date(translateDate);
    newDate = newDate.valueOf();
    newDate = newDate + num * 24 * 60 * 60 * 1000;
    newDate = new Date(newDate);
    //如果月份长度少于2，则前加 0 补位
    if ((newDate.getMonth() + 1).toString().length == 1) {
monthString = 0 + "" + (newDate.getMonth() + 1).toString();
    } else {
monthString = (newDate.getMonth() + 1).toString();
    }
    //如果天数长度少于2，则前加 0 补位
    if (newDate.getDate().toString().length == 1) {
dayString = 0 + "" + newDate.getDate().toString();
    } else {
dayString = newDate.getDate().toString();
    }
    dateString = newDate.getFullYear() + "-" + monthString + "-" + dayString;
    return dateString;
}

function reduceByTransDate(dateParameter, num) {
    var translateDate = "", dateString = "", monthString = "", dayString = "";
    translateDate = dateParameter.replace("-", "/").replace("-", "/");
    var newDate = new Date(translateDate);
    newDate = newDate.valueOf();
    newDate = newDate - num * 24 * 60 * 60 * 1000;
    newDate = new Date(newDate);
    //如果月份长度少于2，则前加 0 补位
    if ((newDate.getMonth() + 1).toString().length == 1) {
monthString = 0 + "" + (newDate.getMonth() + 1).toString();
    } else {
monthString = (newDate.getMonth() + 1).toString();
    }
    //如果天数长度少于2，则前加 0 补位
    if (newDate.getDate().toString().length == 1) {
dayString = 0 + "" + newDate.getDate().toString();
    } else {
dayString = newDate.getDate().toString();
    }
    dateString = newDate.getFullYear() + "-" + monthString + "-" + dayString;
    return dateString;
} 

//得到日期  主方法
function showTime(pdVal) {
    var trans_day = "";
    var cur_date = new Date();
    var cur_year = new Date().format("yyyy");
    var cur_month = cur_date.getMonth() + 1;
    var real_date = cur_date.getDate();
    cur_month = cur_month > 9 ? cur_month : ("0" + cur_month);
    real_date = real_date > 9 ? real_date : ("0" + real_date);
    eT = cur_year + "-" + cur_month + "-" + real_date;
    if (pdVal == 1) {
trans_day = addByTransDate(eT, 1);
    }
    else if (pdVal == -1) {
trans_day = reduceByTransDate(eT, 1);
    }
    else {
trans_day = eT;
    }
   //处理
    return trans_day;
}

调用示例：

//当前日期
var tcur=showTime(0);
//前一天
var tqyt=showTime(-1);
//后一天
var thyt=showTime(1);

附，JS得到当前日期时间的小例子

function currentTime() {
    var d = new Date();
    var vYear = d.getFullYear();
    var vMon = d.getMonth() + 1;
    var vDay = d.getDate();
    var h = d.getHours(); www.jquerycn.cn
    var m = d.getMinutes();
    var se = d.getSeconds();
    var s = vYear+"-"+ (vMon < 10 ? "0" + vMon : vMon)+"-" + (vDay < 10 ? "0" + vDay : vDay)+" " + (h < 10 ? "0" + h : h)+":" + (m < 10 ? "0" + m : m)+":" + (se < 10 ? "0" + se : se);
    return s;
}