cant get the lastest DataView values

the first time,it's ok. but when I change other field or remove some field,I can't get the lastest DataView values by options.dataViews[0]

the code is:

 var cols = options.dataViews[0].metadata.columns
 var names = "";
 cols.forEach(col => {
   names = names + "/" + col.displayName;
 });

 this.target.innerHTML=names; 

Thanks in advance   

 v-viig