JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://unpkg.com/vue@2.1.3/dist/vue.js"></script>
<div id="app">

  <input type="text" id="contactNum" @input="update(addr, 'contactNum', $event)" name="contactNum">

  <input type="text" id="test" v-model="test" name="test">
  <br/> {{addr}}
  <br/> {{addr.contactNum}}
  <br/> {{test}}
</div>

JavaScript

var vm = new Vue({
  el: '#app',
  data: {
    addr: {},
    test: ""
  },
  methods: {
    update: function(obj, prop, event) {
      Vue.set(obj, prop, event.target.value);
    }
  }
});