Comparing two input values in a form validation with AngularJS

You should be able to use ng-pattern/regex for comparing 2 input values

Email:<input type="email" name="email1" ng-model="emailReg">
Repeat Email:<input type="email" name="email2" ng-model="emailReg2" ng-pattern="emailReg">

and validation with:

<span ng-show="registerForm.email2.$error.pattern">Repeat Email should have the same value with email!</span>

One way to achieve this is with a custom directive. Here's an example using a custom directive (ng-match in this case):

<p>Email:<input type="email" name="email1" ng-model="emailReg">
Repeat Email:<input type="email" name="email2" ng-model="emailReg2" ng-match="emailReg"></p>

<span data-ng-show="myForm.emailReg2.$error.match">Emails have to match!</span>

NOTE: It's not generally recommended to use ng- as a prefix for a custom directive because it may conflict with an official AngularJS directive.

Update

It's also possible to get this functionality without using a custom directive:

HTML

<button ng-click="add()></button>
<span ng-show="IsMatch">Emails have to match!</span>

Controller

$scope.add = function() {
  if ($scope.emailReg != $scope.emailReg2) {
    $scope.IsMatch=true;
    return false;
  }
  $scope.IsMatch=false;
}