用JavaScript+layui实现一个日期计算的工具

<div>
		<label>计算日期的小工具</label>
		<br />
		<button  type="button" name="" id=""  οnclick="datectrol('距离中秋日期','Sep 24,2018')">中秋节</button>
		<button  type="button" name="" id=""  οnclick="datectrol('距离重阳节日期','Oct 17,2018')">重阳节</button>
		<button  type="button" name="" id=""  οnclick="datectrol('距离圣诞节日期','Dec 25,2018')">圣诞节</button><br />
		<button  type="button" name="" id=""  οnclick="datectrol('距离春节日期','Feb 4,2019')">春节</button>
		<button  type="button" name="" id=""  οnclick="datectrol('距离除夕日期','Feb 5,2019')">除夕</button>
		<button  type="button" name="" id=""  οnclick="datectrol('距离元旦日期','Jan 1,2019')">元旦</button><br />
		<input type="button" name="" id="userdate" value="查询" οnclick="convertdate(this.value)" class="inputcss"/>
		<input type="date" id="datetime" value="" placeholder="自己输入"  class="layui_input"  οnchange="valdate()"/>
		</div>

div{text-align: center;}
			label{font-size: 2rem;font-family: "agency fb";}
			label:hover{color: #1E9FFF;}
button {display: inline-block;height: 38px;line-height: 38px;padding: 0 18px;
				    background-color: #1E9FFF; color: #fff;white-space: nowrap; text-align: center;
				    font-size: 14px;border: none;border-radius: 2px;cursor: pointer;opacity: .9;
				    width: 8rem;height: 4rem;margin-left: 1rem;margin-top: 1rem;}
button:hover{width: 9rem;height: 4.5rem;border-color: #F72359;}	 	 
.inputcss{display: inline-block;height: 38px;line-height: 38px;padding: 0 18px;
				      background-color: #1E9FFF; color: #fff;white-space: nowrap; text-align: center;
				      font-size: 14px;border: none;border-radius: 2px;cursor: pointer;opacity: .9;
				      width: 8rem;height: 4rem;margin-left: 1rem;margin-top: 1rem;}   
.inputcss:hover{width: 9rem;height: 4.5rem;border-color: #F72359;}
.input_date{margin-left: 1rem;}
.layui_input{display: block;width: 12rem;padding-left: 10px;height: 38px;line-height: 38px;line-height: 36px\9;
						 border: 1px solid #e6e6e6;background-color: #fff;border-radius: 2px;margin-top: 1rem;margin-left: 45%;}

/*计算时间*/
		function datectrol(name,val){
			BirthDay=new Date(val);//元旦的日期
			today=new Date();//当前的日期
			timeold=(-today.getTime()+BirthDay.getTime());
			sectimeold=timeold/1000;
			secondsold=Math.floor(sectimeold);
			msPerDay=24*60*60*1000;
			d_daysold=timeold/msPerDay;
			daysold=Math.floor(d_daysold);
			d_hrsold=(d_daysold-daysold)*24;
			hrsold=Math.floor(d_hrsold);
			d_minsold=(d_hrsold-hrsold)*60;
			minsold=Math.floor((d_hrsold-hrsold)*60);
			seconds=Math.floor((d_minsold-minsold)*60);
			layer.open({
			  skin: 'demo-class',
			  title:name,
			  content: ''+name+'还有:'+daysold+'天'+hrsold+'小时'+minsold+'分'+seconds+'秒'
			});  
		}
		/*将时间填进去*/
		function valdate(){
			$("#userdate").val($("#datetime").val());
		}
		/*日期组件*/
		function datechooice(){
			laydate.render({ 
			  elem: '#datetime'
			  ,type: 'date' //默认，可不填
			});
		}
		/*时间转换*/
		function convertdate(val){
			console.log(val);
			if(val == "查询" || val == null || val == undefined){
				layer.msg("请选择日期再操作");
				return false;
			}
			var condate = val.split("-");
			var year = condate[0];
			var month = condate[1];
			var day = condate[2];
			var conmonth;
			switch(month){
			  case "01":
			  month = "Jan";
			  break;
			  case "02":
			  month = "Feb";
			  break;
			  case "03":
			  month = "Mar";
			  break;
			  case "04":
			  month = "Apr";
			  break;
			  case "05":
			  month = "May";
			  break;
			  case "06":
			  month = "Jun";
			  break;
			  case "07":
			  month = "Jul";
			  break;
			  case "08":
			  month = "Aug";
			  break;
			  case "09":
			  month = "Sep";
			  break;
			  case "10":
			  month = "Oct";
			  break;
			  case "11":
			  month = "Nov";
			  break;
			  case "12":
			  month = "Dec";
			  break;
			  default:
			  month = "|"
			}
			/*将数据格式化成需要的格式*/
			var userdatetime = month+" "+day+","+year;
			datectrol(name,userdatetime)
		}

var condate = val.split("-");

var year = condate[0];
var month = condate[1];
var day = condate[2];

var userdatetime = month+" "+day+","+year;