Vue

HTML

<div id="app">
  <ol>
    <li v-for="student in students">
      <strong>Mobile</strong>
    </li>
  </ol>
</div>

Vue

new Vue({
  el: "#app",
  data: {
    students: [
      { contact: {
      		mobile: '123456',
          phone: '654321',
      }},
      { contact: {
      		mobile: null,
          phone: null,
      }},
      { contact: {}}
    ]
  }
})