title: Change Nan to String
body: <p>I can check the validation of the number, How can I change to string in the same function?</p>
  
  <pre><code>hasValidPhone: function() {
      var isValidPhone = /^\+?[\d-|,|]{7,15}$/.test(this.val());
      return this.length &gt; 0 ? isValidPhone : false;
  },
  </code></pre>