<view class="xiding {{oneFixed}}" id="tab"> 
  <van-row custom-class="goods_row" >    
   <van-col span="12" custom-class="title-1">
    食療方法   
   </van-col>
   <van-col span="12" custom-class="title-2" >   
    動作方法   
   </van-col>
  </van-row>
</view>

/* 吸頂開始 */
.xiding
{
width: 100%;
height: 30px;
background: white;
}
.title-1
{
 text-align: center;
}
.title-2
{
  text-align: center;
}
/* 吸頂 */
.Fixed
{
 position: fixed;
 top: 0;
 z-index: 2;
}
/* 吸頂結(jié)束 */

oneFixed:"",
  tabTop:"0",
  // 吸頂動態(tài)監(jiān)聽函數(shù)
onPageScroll:function(event)
{
 console.log(event.scrollTop > this.data.tabTop)
 if(event.scrollTop>this.data.tabTop)
 {
  if(this.data.tabFix)
  {
   return
  }
  else{
   this.setData({
    oneFixed:"Fixed"http://添加吸頂類
   })
  }
 }
 else
 {
  this.setData({
   oneFixed:''
  })
 }
},


/**
  * 生命周期函數(shù)--監(jiān)聽頁面顯示
  */
 onShow: function () {
  let This=this;
   const query=wx.createSelectorQuery();
   query.select('#tab').boundingClientRect(function(res)
   {
    This.data.tabTop=res.top//255
   }
   ).exec();
 },