Emails Validation Directive
HTML
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.8/angular.min.js"></script>
<div class="container" ng-app="myApp">
<div>
<form id="myForm" name="myForm" novalidate ng-controller="FormController" ng-submit="submitForm()">
<div class="form-group">
<label for="emails">Email(s)</label>
<input id="emails" class="form-control" name="emails" type="text" placeholder="Enter Email(s)" ng-model="newUser.emails" ng-required="true" />
<span class="help-block" ng-show="myForm.emails.$error.required">Email address is required.</span>
<span class="help-block">Enter comma separated emails.</span>
<span class="help-block">Maximum 10 email addresses are allowed.</span>
</div>
</form>
</div>
</div>
JavaScript
var app = angular.module("myApp", []);
app.controller("FormController", ["$scope", function($scope) {
$scope.newUser = {
emails: '',
};
}]);