<div class="container">
  <br />
  <form (ngSubmit)='loginUser()'
  [formGroup]='loginForm' novalidate class="form">
  <label>Username:
      <input formControlName='username' type="text"
               placeholder="Enter Email" />
      <div class="alert  alert-danger"
              *ngIf="loginForm.get('username').hasError('required')
              && loginForm.get('username').touched">
              username is required and min length is 4.
      </div>
      </label><br>
      <label>Password:
      <input formControlName='password' type="password"
           placeholder="Enter Password" />
      <div class="alert  alert-danger"
      *ngIf=" !loginForm.get('password').valid &&
      loginForm.get('password').touched">
          Password is required and should less than 8 characters
      </div>
      </label><br>

      <button [disabled]='loginForm.invalid' class="btn btn-default">Login</button>
  </form>
</div>