var app5 = new Vue({
 el: '#app5',
 data: {
  shoppingList: [
   "Milk", "Donuts", "Cookies", "Chocolate", "Peanut Butter", "Pepto Bismol", "Pepto Bismol (Chocolate flavor)", "Pepto Bismol (Cookie flavor)"
  ],
  key: ""
 },
 computed: {
  filterShoppingList: function () {
   // `this` points to the vm instance
   var key = this.key;
   var shoppingList = this.shoppingList;
   return shoppingList.filter(function (item) {
    return item.toLowerCase().indexOf(key.toLowerCase()) != -1
   });;
  }
 }
})

<div id="app5">
  <h2>Vue-for</h2>
  <ul>
   <li v-for="item in shoppingList">
    {{ item }}
   </li>
  </ul>
  <h2>Vue-for filter实现</h2>
  <ul>
   Filter Key<input type="text" v-model="key"> 
   <li v-for="item in filterShoppingList">
    {{ item }}
   </li>
  </ul>  
 </div>