wxml:

    
    
     
        
          
       
              {
   {index}}    
           
                   
        {
   {citys.city_name}}    
         
      
      
         
                 
                      
       {
   {index}}             
          
        
     
    

js:

//字母锚链定位  topZmClick: function (event) {    var letter = event.currentTarget.dataset.letter;    this.setData({      toView: letter    })  },

wxss:

scroll-view {  height: 600px;}

注：scroll-view必须要设置高度，不然无效