<fieldset>
  <form name="contactForm" novalidate ng-submit="submitFunction()">
    <div class="errors" ng-show="errorMessage">
      <span>{{ errorMessage }}</span>
    </div>

    <div class="input string contact_name">
      <label for="contact_name">
        Contact name
      </label>
      <input required class="string" type="text" name="contact[name]" id="contact_name" ng-model="contactObject.name">
    </div>

    <div class="input string">
      <label for="contact_phone">
        Phone Number
      </label>
      <input required class="string" type="text" name="contact[phone]" id="contact_phone" ng-model="contactObject.phone">
    </div>

    <div class="input string contact_email">
      <label for="contact_email">
        Email
      </label>
      <input required class="string" type="email" name="contact[email]" id="contact_email" ng-model="contactObject.email">
    </div>

    <input type="submit" value="{{ submitValue }}"/>

  </form>
</fieldset>

<fieldset>
  <form name="contactForm" novalidate ng-submit="submitFunction()">
    <div class="errors" ng-show="errorMessage">
      <span>{{ errorMessage }}</span>
    </div>

    <div class="input string contact_name">
      <label for="contact_name">
        Contact name
      </label>
      <input required class="string" type="text" name="name" id="contact_name" ng-model="contactObject.name">
      <div class="error-message" ng-show="contactForm.$submitted || contactForm.name.$touched">
        <div ng-show="contactForm.name.$error.required">Name can't be blank.</div>
      </div>
    </div>

    <div class="input string">
      <label for="contact_phone">
        Phone Number
      </label>
      <input required class="string" type="text" name="phone" id="contact_phone" ng-model="contactObject.phone">
      <div class="error-message" ng-show="contactForm.$submitted || contactForm.phone.$touched">
        <div ng-show="contactForm.phone.$error.required">Phone can't be blank.</div>
      </div>
    </div>

    <div class="input string contact_email">
      <label for="contact_email">
        Email
      </label>
      <input required class="string" type="email" name="email" id="contact_email" ng-model="contactObject.email">
      <div class="error-message" ng-show="contactForm.$submitted || contactForm.email.$touched">
        <div ng-show="contactForm.email.$error.required">Email can't be blank.</div>
        <div ng-show="contactForm.email.$error.email">Email not on the right format.</div>
      </div>
    </div>

    <input type="submit" ng-disabled="contactForm.$invalid" value="{{ submitValue }}"/>

  </form>
</fieldset>

Add frontend validations on the form
Add frontend validations on the form
