获取当前一周时间 不含当天

val 如果形参存在就是代表为开始时间

 getWeekTime: function (val, format) {
      var now = new Date();
      var dd = 0;
      var time = '';
      if (val) {
        dd = -7;
      } else {
        dd = -1;
      }
      now.setDate(now.getDate() + dd);
      var year = now.getFullYear();
      var month = now.getMonth() + 1;
      var day = now.getDate();
      if (month < 10)
        month = "0" + month;
      if (day < 10)
        day = "0" + day;
      if (val) {
        time = year + "-" + month + "-" + day + ' 00:00:00';
      } else {
        time = year + "-" + month + "-" + day + ' 23:59:59';
      }
      return time;
    },