How to validate forms step by step with bootstrap and angular form?

I find this example step-by-step form with bootstrap and angularjs

How can I validate the email before jump to step 2 ?? or block the step jump until the fields are full??

function RegisterCtrl($scope, $location) {

  $scope.steps = [
    'Step 1: Team Info',
    'Step 2: Campaign Info',
    'Step 3: Campaign Media'
  ];

....some code

First, define your model in your controller:

function RegisterCtrl($scope, $location) {
    $scope.step1 = {
        name: '',
        email: '',
        password: '',
        passwordc: ''
     };
    //...

Bind it to your form fields:

<input type="text" id="inputEmail" ng-model="step1.email" placeholder="Email">

Next, do your validation inside gotoStep():

  $scope.goToStep = function(index) {
        if (!$scope.step1.email.match(/[a-z0-9\-_]+@[a-z0-9\-_]+\.[a-z0-9\-_]{2,}/)) {
              return window.alert('Please specify a valid email');
        }
        //...

Obviously alert is not great so use jQuery to focus() and add the Bootstrap classes (control-group warning) to highlight the field.

http://jsfiddle.net/xayzP/

You should use directives to test your form field vadility, e.g:

app.directive('email', function() {
    return {
        require: 'ngModel',
        link: function(scope, elm, attrs, ctrl) {
            ctrl.$parsers.unshift(function(viewValue) {
                if (viewValue && viewValue.match(/[a-z0-9\-_]+@[a-z0-9\-_]+\.[a-z0-9\-_]{2,}/)) {
                    // it is valid
                    ctrl.$setValidity('email', true);
                    return viewValue;
                } else {
                    // it is invalid, return undefined (no model update)
                    ctrl.$setValidity('email', false);
                    return undefined;
                }
            });
        }
    };
});

In your html, you need to add the directive to your input field. You can show error messages if a field is not valid using the myForm.email.$error object:

<input type="text" name="email" id="inputEmail" placeholder="Email" ng-model="email" email required>
<span ng-show="myForm.email.$error.email" class="help-inline">Email invalid</span>
<span ng-show="myForm.email.$error.required" class="help-inline">Email required</span>

You can disable the next link until the form is valid by using myForm.$invalid on ng-class:

<li ng-class="{disabled: myForm.$invalid}" >
   <a ng-model="next" ng-click="incrementStep(myForm)">Next Step &rarr;</a>
</li>

See example.