<v-app id="app">
  <v-container>
    <v-text-field
      ref="password"
      v-model="password"
      :rules="[rules.required, rules.min]"
      type="password"
      label="Password"
      hint="At least 8 characters"
      counter
    ></v-text-field>
    <pre v-if="$refs.password">
      hasError: {{$refs.password.hasError}}
      valid: {{$refs.password.valid}}
    </pre>
  </v-container>
</v-app>