IOS真机上显示为NaN-NaN-NaN

在一个功能上实现显示日期跟星期几，开发完后在开发工具上显示没问题，在安卓机上跑也没什么问题，但在IOS系统的苹果机上显示，时间跟星期几显示为NaN-NaN-NaN，求解
图：

贡上代码
wxml:

<view class="container">
<view class="top">
<view>{{weather.date}} {{weather.week}}</view>
<view>{{weather.city}}</view>
<!--<view>{{weather.updatedate}}</view>-->
</view>
</view>
js:

tempweather["date"] = utils.formatDate(basic["update"]["loc"]);
//当天日期
tempweather["week"]=utils.formatWeekdaybydate(basic["update"]["loc"]);
//周几

function formatDate(sdate) {
  var vdate= new Date(sdate)
  var year = vdate.getFullYear()
  var month = vdate.getMonth() + 1
  var day = vdate.getDate() 
  return [year, month, day].map(formatNumber).join('-')
}

function formatWeekdaybydate(sdate) {
    var vdate = new Date(sdate);
    var weekday = ["周日", "周一", "周二", "周三", "周四", "周五", "周六"];
    var index = vdate.getDay();
    return weekday[index];
}