with very simple component

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/accounting.js/0.4.1/accounting.min.js"></script>
<script src="https://unpkg.com/vue/dist/vue.js"></script>

<div id="app">
  <input type="text" v-model="parentmsg">
  <child :message-text="parentmsg"></child>
</div>

JavaScript

Vue.component('child', {
  template: `
   	<div>
   		sfasf {{messageText}} 
    </div> 
  `,
  props: ["messageText"]
})

new Vue({
  el: '#app',
  data: {
    parentmsg: "Initial Val"
  }
})