<form name="signUp" ng-submit="submitForm()">

<div class="form-group">

<label >用戶名：</label>

<input type="text" name="username"?

ng-model="username"?

ng-class="{ 'error' : signUp.username.$invalid &&?

signUp.username.$touched }"

ng-minlength=4

required?

class="form-control">

</div>

</form>