1.獲取今天的日期

     function getTodayDate(symbol) {
        symbol = symbol || '-';
        var nowDate = new Date(),
            year = nowDate.getFullYear(),
            month = nowDate.getMonth() + 1,
            day = nowDate.getDate();
        month = month < 10 ? '0' + month : month;
        day = day < 10 ? '0' + day : day;
        return year + symbol + month + symbol + day;
    }

    getTodayDate('-') ;

2.獲取之前N月(n<0)或者之後N月(n>0)

function getAnyMonth(symbol,n) {


  symbol = symbol||'-';
  var nowDate = new Date();
  nowDate.setMonth(nowDate.getMonth()+n);
  var year = nowDate.getFullYear(),
      month = nowDate.getMonth()+1;
  month = month < 10 ? '0' + month : month;
  return year + symbol + month;
}

//獲取現在之前兩個月：
getAnyMonth('', -2);

3.獲取之前N天(n<0)或者之後N天(n>0)

    function getAnyDay(symbol, n) {
        symbol = symbol || '-';
        var nowDate = new Date();
        nowDate = nowDate.setDate(nowDate.getDate() + n);
        nowDate = new Date(nowDate);

        var y = nowDate.getFullYear(),
            m = nowDate.getMonth() + 1,
            d = nowDate.getDate();
        m = m < 10 ? '0' + m : m;
        d = d < 10 ? '0' + d : d;
        return y + symbol + m + symbol + d;
    }

    //獲取現在之前5天：
    getAnyDay('-', -5);

4. 獲取之前N小時(n<0)或者之後N小時(n>0)

    function getAnyHour(symbol, n) {
        symbol = symbol || '-';
        var nowDate = new Date();
        nowDate = nowDate.setHours(nowDate.getHours() + n);
        nowDate = new Date(nowDate);
        var y = nowDate.getFullYear(),
            m = nowDate.getMonth() + 1,
            d = nowDate.getDate(),
            h = nowDate.getHours(),
            mi = nowDate.getMinutes();
        m = m < 10 ? '0' + m : m;
        d = d < 10 ? '0' + d : d;
        h = h < 10 ? '0' + h : h;
        mi = mi < 10 ? '0' + mi : mi;
        return y + symbol + m + symbol + d + ' ' + h + ':' + mi;
    }

    //獲取現在之前5小時：
    getAnyHour('-', -5);