title: Vue.js - Element UI - Form validation regexp
body: <p>I'd like to validate a form using <code>vue-js 2.3</code> and <code>element-ui</code></p>
  <p>Apparently, they use <a href="https://github.com/yiminghe/async-validator" rel="noreferrer">async-validator</a> to validate the form.  The documentation is <a href="http://element.eleme.io/#/en-US/component/form" rel="noreferrer">here</a>.</p>
  <h3>Example</h3>
  <p><a href="https://jsfiddle.net/skd3nyqh/" rel="noreferrer">https://jsfiddle.net/skd3nyqh/</a></p>
  <h3>Problem</h3>
  <blockquote>
  <p>Uncaught Error: Unknown rule type  D*([2-9]d{2})(D*)([2-9]d{2})(D*)(d{4})D*</p>
  </blockquote>
  <p>I do not know how to validate a field with <code>regexp</code>. I find the documentation not explicit enough on that topic.</p>