//指定时间大于当前时间为正,指定时间小于当前时间为负
dateDiff: function (targetDate) {
      let date1 = new Date(targetDate);
      let date2 = new Date();
      date1 = new Date(date1.getFullYear(), date1.getMonth(), date1.getDate());
      date2 = new Date(date2.getFullYear(), date2.getMonth(), date2.getDate());
      const diff = date1.getTime() - date2.getTime(); //目标时间减去当前时间
      const diffDate = diff / (24 * 60 * 60 * 1000);
      return diffDate;
},

const diffDate = Math.abs(diff / (24 * 60 * 60 * 1000));//取正数

第二个

* 获取指定日期(字符串类型)到当前时间的天数
			 * @param {Object} sDate1 格式:2018-01-04
			 */
			 dateDiff : function(sDate1) {
			 	var date2 = new Date();
			 	var date1 = new Date(Date.parse(sDate1.replace(/-/g,   "/")));
			 	var iDays = parseInt(Math.abs(date2.getTime()- date1.getTime()) /1000/60/60/24); 
			 	return iDays;
			 },