Vue.filters(id , [definition])
//id {string}
//definition {function}

//index.js
// 引入所有的过滤函数
import readMore from './readMore';
// 导出在一个对象上
export default {
  readMore
};
//readMore.js
//查看更多文字显示'...'
let readMore = (text,length,suffix) => {
 if(text) {
  if(text.length <= length) return text;
  return text.substring(0,length) + suffix;
 }
 return text;
 };
export default readMore;

//全局注册自定义的过滤器
import filters from './filters';
for(let key in filters){
 Vue.filter(key, (val,value1,value2) => {
 return filters[key](val,value1,value2);
 });
}

//在test.vue里面使用
  <p html="readMore('文字文字' ,60,`...<font style='color:rgba(25,123,207,1);'>全文</font>`)"></p>
<span>#<span class="add">{{'文字文字' | readMore(15,'...')}}</span>#</span>