Edit in JSFiddle

new Vue({
   el: '#app',
   data: {
     message: 'Hello',
     greeting: 'welcome'
   },
   filters: {
     capitalize: function (value) {
        return value.toUpperCase()
      }
   }
 });
<div id="app">
   <p>{{ message | capitalize }}</p>
   <p>{{ greeting | capitalize }}</p>
</div>