writing validation for input element using angularjs code example

Example 1: angularjs form validation on submit

<div class="container" ng-app>

  <h1><span><img src="https://s3-us-west-2.amazonaws.com/s.cdpn.io/15309/angular-logo.svg" alt="Angular.js Logo" /></span> Angular.js - Web Form</h1>

  <form role="form" name="form" id="contact-form" novalidate>
    <div class="form-group">
      <label for="FirstName">First name</label>
      <input type="text" class="form-control" name="FirstName" id="FirstName" placeholder="enter first name" ng-model="firstName" required>
    </div>

    <div class="form-group">
      <label for="LastName">Last Name</label>
      <input type="text" class="form-control" name="LastName" id="LastName" placeholder="enter last name" ng-model="lastName" required>
    </div>

    <div class="form-group">
      <label for="EmailAddress">Email address</label>
      <input type="email" class="form-control" id="EmailAddress" name="EmailAddress" placeholder="enter email" ng-model="emailAddress" ng-model-options="{ updateOn: 'blur' }" required>
    </div>

    <div class="checkbox">
      <label>
        <input type="checkbox" required> Check me out
      </label>
    </div>


    <button type="submit" class="btn btn-default" ng-disabled="form.$invalid">Submit</button>

  </form>

</div>

Example 2: angularjs show form validation errors

<ul>
  <li ng-repeat="(key, errors) in form.$error track by $index"> <strong>{{ key }}</strong> errors
    <ul>
      <li ng-repeat="e in errors">{{ e.$name }} has an error: <strong>{{ key }}</strong>.</li>
    </ul>
  </li>
</ul>